Fix bug in "ignore" option behavior

Ensure source code between JSHint "ignore" directives even in the
following cases:

- the line ends in a character sequence that superficially appears to
  be an "end multiline comment" token
- the line ends with a comment that is defined with the multiline
  comment tokens but only spans a single line

Resolves GH-1396
Resolves GH-1691
Merge branch 'gh-1691-fix-ignore' of https://github.com/jugglinmike/jshint

* 'gh-1691-fix-ignore' of https://github.com/jugglinmike/jshint:
  Fix bug in "ignore" option behavior