Minor refactoring

Hi,

I do most of my work on topic branches and then merge that into a development branch, leaving master as the release candidate branch, hence why the last commit is to add `develop` to Travis-CI (for my convenience). It's a pretty standard Git workflow nowadays, and shouldn't affect anything until you add a `develop` branch (which I would advocate) but feel free to skip that commit if it doesn't suit you.

The other commits are just a little bit of clean up in the code, nothing drastic.

Regards,
Iain