Add support for ..= syntax

Add ..= to the parser

Add ..= to libproc_macro

Add ..= to ICH

Highlight ..= in rustdoc

Update impl Debug for RangeInclusive to ..=

Replace `...` to `..=` in range docs

Make the dotdoteq warning point to the ...

Add warning for ... in expressions

Updated more tests to the ..= syntax

Updated even more tests to the ..= syntax

Updated the inclusive_range entry in unstable book

src/libsyntax/print/pprust.rs

@@ -203,6 +203,8 @@ pub fn token_to_string(tok: &Token) -> String {
         token::Dot                  => ".".to_string(),
         token::DotDot               => "..".to_string(),
         token::DotDotDot            => "...".to_string(),
+        token::DotDotEq             => "..=".to_string(),
+        token::DotEq                => ".=".to_string(),
         token::Comma                => ",".to_string(),
         token::Semi                 => ";".to_string(),
         token::Colon                => ":".to_string(),