103/3

[Matthew Flatt <mflatt@cs.utah.edu>]

In CVS, the exp-tagged MrEd/MzScheme source is now version 103/3. The
main change is `(yield 'wait)' in MrEd.

MrEd changes:

 * Added 'wait as a possible argument to `yield'. When called in the
   handler thread of an eventspace, `(yield 'wait)' yields until no
   top-level windows in the eventspace are visible, no timers in the
   eventspace are running, and no callbacks are queued in the
   eventspace.

 * Fixed set-max-undo-history; it wasn't actually resizing the undo
   history buffer.

 * Windows, MacOS: Fixed location of "[Exited]" in stdio window. (PR
   1600)

MzScheme changes:

 * Changed `call-in-nested-thread' to move pre-queued breaks on the
   original thread to the nested thread, and also move leftover breaks
   on a completed nested thread to the original thread.

 * Unix: fixed bug in writing/closing file-stream output ports; if an
   error occurred during write, the port was permanently locked, so
   all port operations blocked.

 * Fixed output to a limited port with a closed reader end; blocked
   threads are now released when the reader end is closed.

 * MacOS: changed `split-path' to preserve the colon suffix on a root
   name. (PR 1597, indirectly)

Matthew