FMSLogo Code

Update with the results of the 8.4.0 test pass.

Add/Fix some LOCAL statements so that global variables are not leaked.

Increment the version to 8.4.0 for a formal release

Fix an inaccurate comment (code drift)

Fix an integer overflow bug in tone when running on GNU/Linux.
This was accomplished by calling gcc's __builtin_mul_overflow, which is abstracted as a macro, in case FMSLogo is compiled with some other compiler.

Fix a typo in a comment

Add a regression test for TONE that tries crash FMSLogo with integer overflow.
This doesn't crash on Windows, but it does on GNU/Linux.

Fix Bug #215; TONE/SOUND now play frequencies <37.
This required making SOUND throws an error when given a negative frequency/duration.

Add a special case to disable treating a leading "-" as negation when it follows a ?.
This fixes a regression (Bug #594) that was introduced when fixing Bug #589.
This restores the previous behavior applying the template "[2 * (? - 1)]".

Fix Bug #244; Halting WAIT now immediately throws a stopping error.