Cleanup: rename file to match class name
Added support for easy standalone uia properties registration

As they can't be in the provider or pattern interface, client-side is basically limited to working with stand-alone properties through UIA (either native or COM wrapper), probably with some convenient self-written extension methods to get them in typed and easier way. Thus the only place where it would more or less declaratively to describe standalone properties is the descendant of CustomPatternBase - the property where registration info would be written into.
So, in order to register standalone property along with custom pattern (most probably because of UIA bug effectively limiting pattern properties to 2 instances per pattern) one have to write something like the following:
[StandaloneProperty("B26C3D40-215A-478B-9C4D-6D91DFDAC3FF", typeof(int))]
public static AutomationProperty StandaloneIntProperty;