Fixed an issue with rendering of backgrounds to empty region.
Made some changes to avoid a rare issue - possibly jvm related.
Merge pull request #851 from synopia/behavior

Some fixes to the behavior system.
Moved default console key to Grave key (`)
Created NUI based console screen, and set it up in the main menu.
Added more screen layer management methods to NUIManager.
Merge branch 'develop' of git@github.com:MovingBlocks/Terasology.git into develop
palette is now a UIList
Fixed GUIManager permission issue.
Created a basic WorldGeneratorPluginLibrary to allow creation of world generator plugins from modules.
Improved RelativeLayoutHint and RowLayoutHint
nodes can be collapsed/expanded using right mouse click
copy subtrees using SHIFT
Added java.lang.annotations to the api packages.
Fixed GUIManager permissions
Added permission needed to send events.
link subtrees using SHIFT, does not work fully
Merge remote-tracking branch 'upstream/develop' into behavior
updated to latest changes