Add simple tests to make sure themes don't contain language errors.

[fireflowerr]

I made a very basic test to just source and apply each theme and cycle through various modes, ensuring that there is no exception. As an aside, if the role of maintainer for this project is still open, I am interested in taking on the job.

[chrisbra]

Thanks, this is very much appreciated and help is always welcome. Let me see how this works.

[fireflowerr]

@chrisbra My apologies! The readme still points to my travis build status. I've updated it to point to the master branch of this main repo. The repo owner needs to authorize travis ci app through the travis ci website, then enable it for this repository. I wasn't sure if I should open a new pull request for this so again sorry if this is the wrong way to go about it.

[chrisbra]

ah yes, I see. I think I have fixed that now...