Physics updates

Added support for
* density
* friction
* restitution

And updated examples with new physics demonstration.
Also, did some small performance improvements and moved all
scripting-related classes to scripting package.
Added light engine :bulb:

In this update I added basic light engine, still work in progress but
you can see it in action in JavaScript demo. Also, drastically increased
performance of scripting.
Updated light engine

In this update I added cone lights and updated light engine a bit and
also examples. Also added license files for some used libraries.
Moved from Netbeans to Eclipse and Gradle
Fix
Removed temp bin file
Small fix for lights
Fixed resources folder
Assets folder
Fixed README
.gitignore update
Gradle dependencies update
No local dependencies
Small data folder fix
Merge pull request #4 from deathbeam/master

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