Multi frame bitmap

[scheffle]

• new multi frame bitmap representation that allows to support more frames per bitmap on current hardware by supporting to layout the frames in the bitmap by rows and multiple columns instead of one column as before. See VSTGUI::CMultiFrameBitmap. All included controls are updated to support it, while the old method is deprecated but still supported for now.
• the image stitcher tool was updated to support the creation of multi row/column frames bitmap