Fixes#18.
- `Language.GraphQL.Encoder` moved to `Language.GraphQL.AST.Encoder`.
- `Language.GraphQL.Parser` moved to `Language.GraphQL.AST.Parser`.
- `Language.GraphQL.Lexer` moved to `Language.GraphQL.AST.Lexer`.
- All `Language.GraphQL.AST.Value` data constructor prefixes were removed. The
module should be imported qualified.
- All `Language.GraphQL.AST.Core.Value` data constructor prefixes were removed.
The module should be imported qualified.
- `Language.GraphQL.AST.Transform` is now isn't exposed publically anymore.