Revert "Changed name for bitmap data from bitmapStream to bitmapData, because bitmapStream is misleading."
Revert "Changed name for bitmap data from bitmapStream to bitmapData, because bitmapStream is misleading."

This reverts commit 7cfdac972d1797504275e02c22cbe526ff2dd4fb.

charlenni/Mapsui,pauldendulk/Mapsui,charlenni/Mapsui