Upgrade Gradle Wrapper to 1.7 and tweak the build script some, encapsulating most idea stuff in its own file
Helps to remember to also rename "mod.txt" to "module.txt" here, lest we no can has modules when running the game
Rename idea.gradle to ide.gradle (hmm, or IDE?) to limit future confusion between it and "gradlew idea" - which goes to build.gradle, not idea.gradle