FMSLogo Code

Remove some uneeded type casting when computing an offset.

Cleanup: Remove some unneeded type casting when computing an offset.

Rework the platform-independent portion of tone() to loop a short wave file on MSW, which can handle it.
This reduces the time and space overhead of tone() for long durations.

Make TONE haltable on GNU/Linux. Also make it not so loud.

Move tone() from ibmterm.cpp to mmwind.cpp, since that's the only place it was called.
I think this was in ibmterm.cpp for historical reasons. In UCBLogo, a file name win32trm.c ends with tone().

Move ltone() from graphics.cpp to mmwind.cpp where it has better coheasion.
ltone() plays a noise, so it belongs near lsound(), not drawing routines.

Add a first pass implementation of tone() that uses wxWidgets.
This enables SOUND and TONE to work on GNU/Linux.
This implementation stutters a bit when given lots of short tones and it's also not safe for integer overflow.

Fix build break on GNU/Linux when precompiled headers aren't used.
gcc got stricter about "#include <file.h>" only being used for system header files.

Fix a comment

Move the initial comment in the code example to an introductory <para>.