Lexer fixes

[CyberShadow]

Thank you for this very nice tool!

Here are some lexer improvements that fix some mismatched coverage in my project.

You are right, though, this is pushing the limits of what regular expressions can do. Adding a proper lexer, or reusing one from bash itself or shellcheck should result in more accurate results.

[coveralls]

Coverage increased (+0.006%) to 99.038% when pulling bab65d8 on CyberShadow:lexer-fixes into 4d00d47 on infertux:master.

[infertux]

Thank you very much for those (horrible) regexps ;)

Do you need me to push a new release with that fix to rubygems.org?

[References #25]

[infertux]

Nevermind, I just pushed release 1.8.1 with your fix. Thanks again.

[CyberShadow]

Thanks! That bumped my coverage by an entire 1.4% :)

[infertux]

aconfmgr looks pretty cool. I'll give it a try :)