[lang] Add missing license headers

lang/src/ast.rs

+// Copyright 2018-2019 Parity Technologies (UK) Ltd.
+// This file is part of pDSL.
+//
+// pDSL is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// pDSL is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with pDSL.  If not, see <http://www.gnu.org/licenses/>.
+
 use crate::parser::keywords;
 
 use proc_macro2::Ident;

lang/src/errors.rs

+// Copyright 2018-2019 Parity Technologies (UK) Ltd.
+// This file is part of pDSL.
+//
+// pDSL is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// pDSL is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with pDSL.  If not, see <http://www.gnu.org/licenses/>.
+
 use proc_macro2::TokenStream;
 use quote::ToTokens;
 use std::result::Result as StdResult;

lang/src/gen.rs

+// Copyright 2018-2019 Parity Technologies (UK) Ltd.
+// This file is part of pDSL.
+//
+// pDSL is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// pDSL is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with pDSL.  If not, see <http://www.gnu.org/licenses/>.
+
 use crate::{
     ast,
     hir,

lang/src/hir.rs

+// Copyright 2018-2019 Parity Technologies (UK) Ltd.
+// This file is part of pDSL.
+//
+// pDSL is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// pDSL is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with pDSL.  If not, see <http://www.gnu.org/licenses/>.
+
 use crate::{
     ast,
     errors::{

lang/src/ident_ext.rs

+// Copyright 2018-2019 Parity Technologies (UK) Ltd.
+// This file is part of pDSL.
+//
+// pDSL is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// pDSL is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with pDSL.  If not, see <http://www.gnu.org/licenses/>.
+
 use proc_macro2::{
     Ident,
     Span,

lang/src/lib.rs

+// Copyright 2018-2019 Parity Technologies (UK) Ltd.
+// This file is part of pDSL.
+//
+// pDSL is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// pDSL is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with pDSL.  If not, see <http://www.gnu.org/licenses/>.
+
 #![recursion_limit = "128"]
 
 extern crate proc_macro;

lang/src/parser.rs

-use crate::proc_macro;
+// Copyright 2018-2019 Parity Technologies (UK) Ltd.
+// This file is part of pDSL.
+//
+// pDSL is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// pDSL is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with pDSL.  If not, see <http://www.gnu.org/licenses/>.
 
-// use proc_macro2::TokenStream;
-use crate::ast;
+use crate::{
+    ast,
+    proc_macro,
+};
 use syn::{
     self,
     parse::{