#22 GetWorkPort() should use GWorlds, not Windows

[Chris Waco]

The routine GetWorkPort() in MQuickDrawUtils.cpp should be
changed to use GWorlds rather than windows. Window
creation is probably a much more time intensive operation
with more potential side effects than NewGWorld.

Note that if we want to support really old (pre-GWorld)
system versions, the code should be left as is.