[plt-scheme] 299.12

The v299-tagged code in CVS for MzScheme and MrEd is now version 299.12.

Changes:

 * Added `hash-table-count' (catches up with v208).

 * Added 'transparent style to editor-canvas%.

 * Added a background-color argument to editor<%>'s `refresh'.

 * Added `set-canvas-background' and `get-canvas-background' to
   canvas<%>.

This version number also syncs several changes that I tagged since
299.11, including the GC upgrade and the change to --enable-shared as
the default configure mode.

Temporary docs in the usual place:

  http://www.cs.utah.edu/~mflatt/tmp/mzscheme-doc.plt
  http://www.cs.utah.edu/~mflatt/tmp/mzlib-doc.plt
  http://www.cs.utah.edu/~mflatt/tmp/mred-doc.plt

Matthew