Added ButtonGroup#clear
Cell, avoid boxing where possible, don't expose primitive type wrappers in public API.
Fixed page size.
Javadoc.
Avoid boxing.
Fixed fill not respecting min size.

This could break existing layouts that relied on the old behavior. If this happens to you, use `.fill().minSize(0)`.
Merge remote-tracking branch 'origin/master'
Use Gwt plugin 0.5, jcenter repository, remove mavenlocal()
Forgot one local
Merge pull request #2313 from Tom-Ski/setup

Use GWT Gradle plugin version 0.5. Remove maven Local as a default repository.  Adds jcenter repository.
Update IOSApplication for UIApplicationLaunchOptions
Merge pull request #2315 from Tom-Ski/robovm

Update IOSApplication for UIApplicationLaunchOptions
Fixed JSON using Class.forName before tagToClass.

closes #2314
Merge remote-tracking branch 'origin/master'
set empty Gdx.* fields and made get[Component]() methods work

HeadlessApplication#get[Input/Graphics/Audio]() returned null even though HeadlessApplication had mock implementations. Correct me if I'm wrong, but I guess this was because the getters were forgotten when those mock implementations were added. I don't think they returned null intentionally because the Gdx.[audio/graphics] fields were set (Gdx.input not though, so it seems it was forgotten as well).
Make Box2DDebugRenderer implement Disposable
Merge branch 'master' of https://github.com/libgdx/libgdx into various
Merge pull request #2316 from dermetfan/master

set empty Gdx.* fields and made get[Component]() methods work in headless backend
Fixed ButtonGroup not removing from the checked buttons list.
Keep names for drawables to make debugging easier.