[ENH] Pluggable Tab Bar Morph ( [er][et] straight from BFAV, works with Keymapping )

[cdshaffer at acm.org]

I loaded this into a 3.7 (final but not Full) image and loaded and
tested my Keymapping package.  The PTBM worked fine.

This is a visually appealing morph and represents a GUI component used
in many applications outside of Squeak.  It might see significantly
greater use in Squeak if it was part of the base image.