Added Waila Integration

The variation description is shown in between the block name and the mod name. Quite handy. Also some other minor improvements:

* Added IDEA files to gitignore, for people who use IDEA (like me)
* Replaced deprecated `assetDir` with `runDir`
* Allowed for version replacing upon build, making it so you only have to change the version number in one place for each update, instead of two.
* Changed API Zip to Sources Jar, as that will probably be used more often anyway.
* Formatting and other small things, just look at the changes.