Fix wrong highlighting for keywords.
Fix wrong highlighting for keywords.

We assume there must be spaces before/after a keyword,
or the keyword is at line begin/end.

So, the followings will not be highlighted as keywords.

  if-up      # 'if' is not a control key word here
  foo:if:bar # 'if' is not a control key word here

jfcherng/Sublime-ShellScriptImproved