* Removes the old 'Region' fields and places them under a 'Mask' option that can do much more.
* Supported Mask types: Region, Image, Source.
* Image and Source mask types allow for a color filter and multiplier.
The Blur Filter can now be applied to a region inside the source itself, the inverse of that region, and/or a feathered version of that region. This allows for easier scene setups where only some parts need to be blurred, but the rest can be left as is.
Fixes#12