FMSLogo Code

Fix build breaks on GNU/Linux that resulted from changing the type of
the scrollbar positions from "UINT" to "int". The change was incomplete
and this revision completes the change.

Add some missing "const" qualifiers to fix compiler warnings with gcc (same as with the other .xpm files)

Change the type of a scroll position from UNIT to int. UNIT is a Windows-specific type and was used because the OWL version of FMSLogo used it. Now that the OWL version has been deleted, it's more natural (and platform-independent) to use what wxWidgets uses, which is int.

Combine the logic within CScreen::OnPaint() and PaintToScreenWindow() so that there's a single function which works for both the full FMSLogo environment and the screen saver. This became possible once both environments stated to use wxWidgets.

Remove the platform-dependent code from ShowMessage() so that it can be called correctly on non-Windows platforms.

Fix bug #437; FMSLogo no longer crashes if BITMAPTURTLE has no bitmap (it now behaves as if it had a zero-sized bitmap)

Fix a typo in a comment

Add a comment

Remove LOCALIZED_EDITOR_TEST_BUTTON. This was only used in the OWL version of FMSLogo and serves no purpose now that the OWL version has been deleted.

Remove the LOCALIZED_STRINGTABLE_* strings which were referenced by the OWL version of FMSLogo, but not by the wxWidgets version. Since the OWL version no longer exists, these strings provide no benefit, but make it harder to localize FMSLogo.