Clean up warnings, update next_body, add more tests

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

src/syn/lexer.rs

@@ -165,6 +165,7 @@ impl<'t> Lexer<'t> {
             });
         };
 
+
         let start = self.pos;
         self.pos.adv_str(token_text);
         let end = self.pos;