Update README, repair symbol links and simplify license headers (#498)

* [chores] update README to new ink! 3.0 syntax

* [*] update all broken LICENSE and README.md symbolic links

* [*] update all license headers

Also be more strict about their dates: 2018-2020 for all

FILE_HEADER

-// Copyright {20\d{2}}-{20\d{2}} Parity Technologies (UK) Ltd.
+// Copyright 2018-2020 Parity Technologies (UK) Ltd.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

README.md

@@ -86,13 +86,13 @@ Below you can see the code using the `ink_lang` version of ink!.
 ```rust
 use ink_lang as ink;
 
-#[ink::contract(version = "0.1.0")]
+#[ink::contract]
 mod flipper {
     use ink_core::storage;
 
     /// The storage of the flipper contract.
     #[ink(storage)]
-    struct Flipper {
+    pub struct Flipper {
         /// The single `bool` value.
         value: bool,
     }
@@ -100,7 +100,7 @@ mod flipper {
     impl Flipper {
         /// Instantiates a new Flipper contract and initializes `value` to `init_value`.
         #[ink(constructor)]
-        fn new(init_value: bool) -> Self {
+        pub fn new(init_value: bool) -> Self {
             Self {
                 value: init_value,
             }
@@ -108,35 +108,30 @@ mod flipper {
 
         /// Instantiates a new Flipper contract and initializes `value` to `false` by default.
         #[ink(constructor)]
-        fn default() -> Self {
+        pub fn default() -> Self {
             Self::new(false)
         }
 
         /// Flips `value` from `true` to `false` or vice versa.
         #[ink(message)]
-        fn flip(&mut self) {
+        pub fn flip(&mut self) {
             self.value = !self.value;
         }
 
         /// Returns the current state of `value`.
         #[ink(message)]
-        fn get(&self) -> bool {
+        pub fn get(&self) -> bool {
             self.value
         }
     }
 
-    /// As in normal Rust code we are able to define tests like below.
-    ///
-    /// Simply execute `cargo test` in order to test your contract.
+    /// Simply execute `cargo test` in order to test your contract using the below unit tests.
     #[cfg(test)]
     mod tests {
         use super::*;
 
         #[test]
         fn default_works() {
-            // Note that `#[ink(constructor)]` functions that above have been
-            // defined as `&mut self` can be used as normal Rust constructors
-            // in test mode.
             let flipper = Flipper::default();
             assert_eq!(flipper.get(), false);
         }

crates/alloc/LICENSE

-../LICENSE
+../../LICENSE
\ No newline at end of file

crates/alloc/README.md

-../README.md
+../../README.md
\ No newline at end of file

crates/core/LICENSE

-../LICENSE
+../../LICENSE
\ No newline at end of file

crates/core/README.md

-../README.md
+../../README.md
\ No newline at end of file

crates/core/benches/bench_bitstash.rs

-// Copyright 2019-2020 Parity Technologies (UK) Ltd.
+// Copyright 2018-2020 Parity Technologies (UK) Ltd.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

crates/core/benches/bench_hashmap.rs

-// Copyright 2019-2020 Parity Technologies (UK) Ltd.
+// Copyright 2018-2020 Parity Technologies (UK) Ltd.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

crates/core/benches/bench_lazy.rs

-// Copyright 2019-2020 Parity Technologies (UK) Ltd.
+// Copyright 2018-2020 Parity Technologies (UK) Ltd.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

crates/core/benches/bench_stash.rs

-// Copyright 2019-2020 Parity Technologies (UK) Ltd.
+// Copyright 2018-2020 Parity Technologies (UK) Ltd.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

crates/core/benches/bench_vec.rs

-// Copyright 2019-2020 Parity Technologies (UK) Ltd.
+// Copyright 2018-2020 Parity Technologies (UK) Ltd.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

crates/core/src/env/api.rs

-// Copyright 2019-2020 Parity Technologies (UK) Ltd.
+// Copyright 2018-2020 Parity Technologies (UK) Ltd.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

crates/core/src/env/arithmetic.rs

-// Copyright 2019-2020 Parity Technologies (UK) Ltd.
+// Copyright 2018-2020 Parity Technologies (UK) Ltd.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

crates/core/src/env/backend.rs

-// Copyright 2019-2020 Parity Technologies (UK) Ltd.
+// Copyright 2018-2020 Parity Technologies (UK) Ltd.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

crates/core/src/env/call/call_builder.rs

-// Copyright 2019-2020 Parity Technologies (UK) Ltd.
+// Copyright 2018-2020 Parity Technologies (UK) Ltd.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

crates/core/src/env/call/common.rs

-// Copyright 2019-2020 Parity Technologies (UK) Ltd.
+// Copyright 2018-2020 Parity Technologies (UK) Ltd.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

crates/core/src/env/call/create_builder.rs

-// Copyright 2019-2020 Parity Technologies (UK) Ltd.
+// Copyright 2018-2020 Parity Technologies (UK) Ltd.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

crates/core/src/env/call/execution_input.rs

-// Copyright 2019-2020 Parity Technologies (UK) Ltd.
+// Copyright 2018-2020 Parity Technologies (UK) Ltd.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

crates/core/src/env/call/mod.rs

-// Copyright 2019-2020 Parity Technologies (UK) Ltd.
+// Copyright 2018-2020 Parity Technologies (UK) Ltd.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

crates/core/src/env/call/selector.rs

-// Copyright 2019-2020 Parity Technologies (UK) Ltd.
+// Copyright 2018-2020 Parity Technologies (UK) Ltd.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.