fixes string and regular expression quoting

The following problems have been addressed:

- coffeescript allows any character inside a string after a '\'. Many
  characters have no meaning and the \ is ignored, however they are
  syntactically correct

- strings can expand multiple lines
      "this is \
      a multi-line string"

- regular expressions can be enclosed in a pair of / 

- the string "\\" was parsed incorrectly because the first
  character was !('"') but if it was a '\' then the special
  meaning was not taken care of....