[client] use types v2 (less alloc) (#269)

* rewrite me

* v2

* PoC works without batch request

* remove `PartialEq` bounds

* add naive benches types

* misc

* remove useless lifetime

* [ws client]: move request ID generation to client

* make tests compile again

* [client transport]: kill leaky abstractions.

* [http client transport]: minor changes in the API.

* [ws client]: fix batch requests.

* fix nits

* [ws client]: generate two request IDs for subscrib

* fix tests

* remove unused types + less alloc for params.

* fix nits

* more tweaks.

* remove unused code

* fix more nits

* remove unused legacy types

* reorg types_v2 mod

* port macros to new types

* fix tests again; more jsonvalue

* [proc macros]: bring back impl Into for params.

* fix build

* [proc macros]: make it work for external crates.

* [types]: remove weird From<Option<T>> to impl.

* cleanup again

* [examples]: remove unused async-std dep

* Update types/src/v2/mod.rs

* [types]: remove unsed dep smallvec

* rewrite me

* [types]: error code impl ser/deser

Manual implementation of serialize/deserialize to get rid of duplicated message string

* [types v2]: re-org with explicit mods

* fix faulty test

* add missed files

* [ws client]: req_manager reserve unsubscribe slot.

* simplify test code

* add tracking issue for TODO

* remove unused deps