Blender Git Loki

Sculpt: Add global automasking options for all brushes

This adds the automasking options to the Sculpt Tool options in a way
that they affect all brushes. This is more convenient when working with
some of these options while switching brushes as they don't need to be
enabled/disabled per brush.
An automasking option is enabled if it is enabled in the brush or in the
sculpt options.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D7304