Polished Pretty

With pretty-printing pretty much completely working, I moved the bulk of the functions into an
internal module, then from 'Language.Rust.Pretty' itself, I only expose the typeclasses 'Pretty' and
'PrettyAnnotated', and a bunch of instances. Ideally, this is going to be enough for most users -
the functionality is exposed, and the Haddock will be short.

Also internally cleaned up some stray functions in Pretty (block-like things are now named
accordingly and mostly unified).

Author: harpocrates

language-rust.cabal

@@ -21,6 +21,7 @@ library
   default-language:    Haskell2010
 
   exposed-modules:     Language.Rust.Pretty
+                       Language.Rust.Pretty.Internal
                        Language.Rust.Syntax.Token
                        Language.Rust.Syntax.Ident
                        Language.Rust.Syntax.Constants

src/Language/Rust/Parser/Parser2.y

@@ -480,6 +480,8 @@ generic_values_after_lt
       | comma(lifetime)                                      { (sequence $1, pure []    , pure []    )  }
       |                                                      { (pure []    , pure []    , pure []    ) }
 
+
+
 -- parse_arg_general(false) -- does not require name
 -- NOT ALL PATTERNS ARE ACCEPTED: <https://github.com/rust-lang/rust/issues/35203>
 arg_general :: { Spanned (Arg Span) }