getKeywords method

[nijikokun]

Rainbow.getKeywords = function(str) {
  str = str.replace(/^\s+|\s+$/g, '').replace(/\s+/g, '|');
  return '\\b(?:' + str + ')\\b';
};

Would be nice to have in the official file for things like:

Rainbow.getKeywords('break case catch class copy const __finally __exception __try');

would return

"\b(?:break|case|catch|class|copy|const|__finally|__exception|__try)\b"