Re-re-re-fix Aero snap issues with Window Manager

It is absolutely mind-boggling that various Aero snap functions send
totally unrelated system messages.  WHY DOES MAXIMIZE NOT SEND THE
SC_MAXIMIZE MESSAGE??  To remedy this I've now added SC_MOVE to the list
of messages, which is inexplicably required for Aero snap maximizing.

<shakes fist and mumbles incoherently>
New Select -> Export menu

...And two new items within the Select -> Export menu: export selected
area as image, and export selection mask as image.

These are a bit more niche than I generally prefer, but as they've
proven immensely helpful to me, perhaps others can find use of them as
well.

This was also a useful test of PhotoDemon's previously rewritten save
engine.  Thanks to that, it is trivial to export any arbitrary image,
while taking full advantage of PD's many save features and formats.

"Export selected area as image" basically saves you the trouble of Copy
-> Paste -> Save As.  Nothing too weird there, but nice to save on some
clicks.

"Export selection mask as image" has been a great help while working on
Selection tool documentation.  Very nice to be able to visualize how
selections work.  (It should also prove valuable when it comes time to
test "magic wand" -type selection tools.)
Improve contrast of "unsaved changes" asterisk
New File -> Open Recent -> Load all recent files option

Thanks to RR for suggesting.  The new tabbed interface makes this much
more practical (and useful) than it would have been previously.

Not only is this helpful to me for testing purposes, but I like that it
ties into PD's "portable" mentality - if you have a bunch of images
open, and you close the program, you can now easily pick up where you
left off at a future date by simply re-loading the full recent images
list.