Coding standards (WIP)

With over 200 contributors and 3 years of active development, the code base has become a bit inconsistent. My mission is to painstakingly update each file to WordPress coding standards. For some reason I thought I could do this all in one weekend. Boy, was I wrong :smile: 

I've decided to submit the PR unfinished to get feedback from everyone else and to see if anyone is interested in helping me on my little mission. As long as no one opposes, I will continue updating the pull request in my spare time.