Add more expressions to parser, add EOL and newline tokens

* Lexer recognizes semicolons as EOL tokens, and newline tokens
* Parser can be configured to ignore newlines (which is also used
  internally)
* Newlines are allowed in lists, tuples, and parenthesized expressions
* Add a bunch of tests for the new stuff

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

src/syn/token.rs

@@ -31,6 +31,8 @@ pub enum TokenKind {
     Splat,
     FSlash,
     Bang,
+    Eol,
+    Newline,
 }
 
 impl Display for TokenKind {
@@ -65,6 +67,8 @@ impl Display for TokenKind {
             Splat => "splat (or times)",
             FSlash => "fslash (or divide)",
             Bang => "not",
+            Eol => "line end",
+            Newline => "newline",
         };
         Display::fmt(s, fmt)
     }