Add lexer, parser, ast, and basic command line interaction

* Add lexer and parser using lrpar crate
* AST is added and constructed via lexer and parser
* Command line program `not` will read a file and parse it

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

src/syn/lexer.l

@@ -1,5 +1,5 @@
 %%
-[\n;]+                      "EOL"
+[\r\n;]+                    "EOL"
 [a-zA-Z_][a-zA-Z0-9_]*      "IDENT"
 :[a-zA-Z_][a-zA-Z0-9_]*     "SYM"
 [0-9]+                      "NUM"