resolves #551: now notes on selected panes can be removed
add "Add..." tab to shapes lab tab control
Merge branch 'master' into Feature-CustomShapes
Merge branch 'dev_1.9' into Feature-CustomShapes
Merge branch 'release' into Feature-CustomShapes
change view from tab control into combo box + flow layout
Merge branch 'release' into Feature-CustomShapes
Merge remote-tracking branch 'origin/master' into dev_1.9
Fixed #530: Zoom to Area has performance issue
backend of multi-category done, need to be verified
some regression due to commit #04b0a32  fixed
add category works fine
add consistency check logic for categories
feature remove category added, need to be tested
change cursor to open hand, when mouse hovered onto Colors lab's fill buttons #563
drill-down and step-back should preserve shadow/border of target shape #406
Merge branch 'release' into Feature-CustomShapes

Conflicts:
	PowerPointLabs/PowerPointLabs/Ribbon1.cs
fixes a bug that may delete the entire shape folder
fixes a bug in consistency check which results in early termination
fixes some logic error in category removing