FMSLogo Code

Replace a call to the win32 MessageBox API with wxMessageBox.
This enables the message box to appear on GNU/Linux.

Get enough of SETFOCUS and WINDOWSET working on GNU/Linux to play snake.lgo.
This amounts to being able to MINIMIZE the commander and SETFOCUS on the screen window.

Implement MyMessageScan on non-MSW platforms using wxWidgets API.
Among other things, this enables the drawing to be seen as drawing instructions are run, instead of only appearing the next time control flow reaches the top level. For example, this enables the game play of the snake.lgo program in the "extras" project.

Fix a build break on GNU/Linux when precompiled headers aren't used.

Fix a misspelling of "independent" in a comment

Restore some broken logic in label() for drawing directly to the screen DC.
This logic is compiled out of the final code; it exists to highlight why the current logic is not like it was in MSWLogo.

Add a regression test for when LABEL is given a word with line breaks.
MSWLogo ignored the line breaks, but after porting LABEL from win32 to wxWidgets, they are now honored.

Cleanup: Replace LogFontToWxFont with wxFont(LOGFONT).
wxWidgets has a constructor which does the same thing, so there's no need to duplicate its internal logic within FMSLogo.

Fix an unintentional change in behavior of LABLESIZE after porting it from win32 to wxWidgets.
wxDC->GetTextExtent(String) returns a bounding box that is larger than what ::GetTextExtentPoint returns.
This was found by the regression tests in label.lgo.

Fix a build break when compiling without precompiled headers