add import button to context menu
Merge branch 'Feature-CustomShapes' of https://github.com/PowerPointLabs/repo into Feature-CustomShapes

Conflicts:
	PowerPointLabs/PowerPointLabs/CustomShapePane.Designer.cs
first version of import
multiple select dragging effect
correct dragging effect
remove rename slide feature
refactor selection rectangle code
#572 half done, need to be tested
fixes single click bug, resolves multiple moving flashes, resolves #572
fixes a potential null pointer bug
resolves #436
add text box to indicate category name
Fixed #573: Cannot add animation slide due to "no matching objects"
category box can be recognised correctly
fixes #436 bugs when import package doesn't have category names
Merge branch 'Feature-CustomShapes' into dev-1.10
Merge branch 'master' into dev-1.10
update version info for dev 1.10.1.0 online