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'
Added proper mouse support to Android backend