Miscellaneous fixes and additions;

* Single quotes are only valid for characters. Characters
  include some escape sequences defined here:
  http://nimrod-lang.org/manual.html#string-literals
* Newlines between patterns for better readability
* Upper and lower case i,u
* Raw strings: double quoted strings prefixed by r do not highlight
  escape sequences differently
* Triple quoted strings: those strings are raw by definition
* Better organized syntaxTest.nim