Update build.gradle

Add source jar generation as an option.

Useful for Mavenisation, when TCon is just referred to by a Maven dependency. This attaches clean sources without decompiling or checking out from Git.
Merge pull request #737 from Sunstrike/patch-2

Update build.gradle
Fixes idle bow sprite
Fixed Smeltery GUI click and drag
Fixed flammabilty of bricks and fancy bricks
Merge pull request #738 from Glassmaker/patch-multifixes

Multifixes