Highlight text token if available

[guilhermesimoes]

Since ruby -wc does not return column numbers, the best we can do for now is parse the warning messages and highlight some text tokens.

Before:

After:

[guilhermesimoes]

This is still a WIP as I may have missed a few other warnings that can also be highlighted.

[guilhermesimoes]

Everything should be good now!

[kaste]

Hi. Sorry this repo obviously had no maintainer at that time.

LGTM. @braver ship it!?

[braver]

I don’t know anything about Ruby or these changes. I’ll ship it and give @guilhermesimoes access to the repo so he can perhaps make changes later if the need arises.