logging: Changed log level for default handler
StackExportFileOptionsWidget: Initialize stack description label correctly.
SubRegionRoiWidget: Eliminate initial inconsistent display as described in ilastik/ilastik#876
HUD: Increase width of coordinate display to 6 digits.
replace byte by 8-bit, insert an underscore before slice index in export
tiling.py: Improved an assertion message.
hud: Spinboxes for x,y,z, and time now delay for 750 ms before signalling with the updated value.
Fixes ilastik/ilastik#666
hud: QuadView coordinate display (shown at the bottom) is now editable, and sets both the slicing pos and cursor pos.
VolumeEditorWidget: Permanently hide the "progress pies".  Instead, show a "busy" progress bar at the bottom of the whole quadview.
Workaround for ilastik/ilastik#694.
layer: Added support for bool type layers.