mySTEP.make: build bundle (with special rules for Frameworks)

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
AppKit: added missing public header files for new target

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
AppKitNibTest: made compile and run on Cocoa

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
AppKit: added shared scheme

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
AppKitNibTest: made compile with mySTEP AppKit and use X11

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
AppKit: accept NSApplication as principleClass

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>