Added bitmap cache with background processes

[akevalion]

This pull request enables a quatree for big visualizations.

This uses 2 bitmaps, 1 bitmap for the entire visualization and second bitmap for a quality visualization. check AbstractMemoryPresenter >> #mouseClick: to propagate the event to the nodes. This is not a general solution for Roassal3, Roassal3 will support R-tree in a future.