Updated keywords in JavaScript definition

* Sort keywords alphabetically (to ease maintenance)
* Added all missing keywords
* Added ECMAScript 5 keywords
* Added true/false/null as explicit keywords

Source: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Reserved_Words

Fixes #270
Merge pull request #271 from apfelbox/javascript-keywords

Updated keywords in JavaScript definition
Simple start for Rip

Recognize comment, builtin, boolean
Recognize boolean, date, time, datetime, number
Recognize regex, symbol, string (crudely)
Recognize keywords
Recognize character
Recognize punctuation and reference