FMSLogo Code

Use BITBLOCK to erase the selection with Sudoku instead of using LABEL in white.
If a font is anti-aliased, using LABEL in white leaves a outline, as is the case on Linux.

Also add some line breaks to improve readability of a long IF statement.

Fix a misspelling of "corresponds" in a comment

Have SHELL include the directory containing FMSLogo in the PATH of the child process on non-MSW platforms.
This makes SHELL act like more like it does on Windows which enables the "restart with correct width/height" pattern that Asteriod Miner and other programs use.

Use the entire destkop size as the working area on non-MSW platforms instead of hard-coding it to 500x500.
As far as I can tell, "working area" is purely a Windows concept.
This fixes a problem where asteriodminer would always start in a tiny window on GNU/Linux because MACHINE claimed there wasn't enough sapce.

Fix a bug where, when the working area was very small (500px wide), asteriod miner would go into an infinite restart loop.
The problem is that it would restart with a size that was too small, and attempt to restart itself with the same size.
Now it restarts with the minimize legal size, which might be too large for the working area, but is better than an infinite loop.

Reimplement the screen DC drawing in BITPASTE and BITCUT as a refresh instead of directly drawing to the wxDC.
On WXGTK, drawing directly to the wxScreenDC outside a paint event doesn't seem to have an effect.
I suspect that MSWLogo drew directly to the screen instead of refreshing it because it was faster. In these cases, I don't expect it's noticably faster because a refresh should result in a BLIT from memory, which is roughly what the direct-to-screen logic was doing.

This change fixes a problem where the score, timing, and lives indicators weren't being rendered in Asteriod Miner on GNU/Linux.

Explicitly refresh the screen after creating the window.
This is needed on GNU/Linux (GTK) to show the turtle in its initial position.

Fix a recent regression in GetScreenWindow where it returned the HWND of the main window, not the screen.
This probably caused many problems, but the one I noticed is that the turtle didn't move until the window was resized.
The fix was implemented by rewriting GetScreenWindow and GetMainWindow in terms of their "Wx" counterparts, which makes the implementation clearer.

Disable anti-aliasing when drawing lines on GTK/Linux.
Although anti-aliasing makes pictures look nicer, it interferes with basic FMSLogo functionality like FILL and BITMAPTURTLE and PENERASE. The problem is that the anti-aliasing leaves a outline around the line that was drawn which those procedures don't expect.

Fix a bug that prevented FMSLogo from shutting down on GNU/Linux when the commander was undocked.