gradle: Added 'init' task results
gradle: Moved code into src/main/java folder

This is the gradle convention for production code source location.
gradle: Activated 'java' plugin

.. and stripped unnecessary beginner comments
Added .gitignore file

Source: https://github.com/github/gitignore/blob/master/Gradle.gitignore
gradle: Added 'application' plugin to create executable applications
gradle: Updated gradle wrapper properties file

According to IntelliJ suggestion
Updated .gitignore file
cleanup: Optimized imports
cleanup: Reformatted code
cleanup: Removed unnecessary semicolons
cleanup: Removed redundant variables
cleanup: Removed redundant return statements
cleanup: Removed unnecessary final modifiers on static methods
cleanup: Use generified Vectors
cleanup: Added final modifier to static fields
cleanup: Simplified MovementManager.joinedCircuit() method