Merge pull request #171 from greboid/master

Update build scripts.
Add a BackBuffer class.

This will move some of the logic out of FrameContainer, and will
be responsible for handling DisplayableEvents in the future.
Merge pull request #172 from csmith/master

Add a BackBuffer class.
Remove some deprecated uses of getConnection().
Fix tests.
Update PMD to 5.2.2.
Merge pull request #174 from csmith/gradle-pmd

Update PMD to 5.2.2.
Merge pull request #173 from csmith/master

Remove some deprecated uses of getConnection().
Fix some PMD errors.
Merge pull request #175 from csmith/gradle-pmd

Fix some PMD errors.
Stop ClientInfo being static.