FMSLogo Code

Change "char" types to "wchar_t" to support Unicode.
This is a first step to supporting Unicode.

Merge in changes from trunk which remove a type cast.

Remove an unneeded type case.

Merge some typo fixes from trunk.

Fix a misleading comment.

Fix a typo in a comment.

Integrate latest changes from trunk into the unicode branch.

Remove CLEARPALETTE from DEMO.
CLEARPALETTE has been a deprecated no-op since FMSLogo 7.0.0.

Remove a #ifdef WXPURE by replaceing MessageBox with nearly equivalent wxMessageBox.
This is not exactly the same because the original used the deprecated MB_ICONQUESTION, which wxWidgets doesn't support.
This is a small step toward to a native GNU/Linux version of FMSLogo.

Add a regression test that SAVE displays a warning if run while the editor is open.