A lot of cleanup and refactoring utility funcs.

Got rid of a bunch of unused code, cleaned up the utility
functions, moved the utilities back into the grammar.pegjs file to
avoid the extra magic of injecting the import statement into the
built parser.

Fixed the binary expression logic to properly handle cases such
as:

``` sql
SELECT * FROM t where -1 * (2 + 3);
SELECT * FROM t where 3 + 4 * 5 > 20;
SELECT * FROM t where v1 = ((v2 * 5) - v3);
```

Updated SQL in specs to contain correct ASTs for specs related
to expression grouping.

Should have broken this into several commits but the changes
are too intertwined to easily break apart now.

Refs #20
Refs #3

Author: nwronski

Gruntfile.js

@@ -107,9 +107,8 @@ module.exports = function(grunt) {
     concat: {
       options: {
         stripBanners: true,
-        // This imports the utilities used by the parser
-        banner: "\nimport * as util from './parser-util';\n\nconst ",
         // This exports the compiled parser
+        banner: "\nconst ",
         footer: "\nexport default parser.parse;"
       },
       build: {

index.js

@@ -2,12 +2,11 @@
  * sqlite-parser
  */
 import parser from './lib/parser';
-import {isFunc} from './lib/parser-util';
 import Tracer from './lib/tracer';
 
 export default function sqliteParser(source, callback) {
   const t = Tracer();
-  const isAsync = isFunc(callback);
+  const isAsync = typeof callback === 'function';
   const opts = { 'tracer': t };
   // Async
   if (isAsync) {