'dist' plugin and added iOS functionality for 'compile' and 'clean'

The `compile` plugin now builds the iOS project using xcodebuild.

I've added a `dist` plugin which (for now) supports only iOS. The plugin creates an archive for the project and then exports that as an .ipa. **Warning**: This is the first time I've built an iOS project using the command line. It may not be the best way to create it, I don't know. The test I've made was to use this plugin to create the .ipa for my game and submitting it to iTC, it's now in 'Waiting for review'.