FMSLogo Code

Stop including graphics.h, since it's no longer needed.

Stop including graphics.h, since it's no longer needed.

Stop including graphics.h, since it's no longer needed.

Stop including graphics.h, since it's no longer needed.

Stop including graphics.h, since it's no longer needed.

Stop including graphics.h, since it's no longer needed.

Move numeric_arg from graphics.cpp to logmath.cpp and make it static.
After recent refactoring, logomath.cpp is the only place remaining that calls it.

Change lscrollx() and lscrolly() to use flonum_arg().
flownum_arg() is preferable to numeric_arg() because it doesn't have the side effect of changing the argument list.
This is part of a larger effort to make the code base simpler by removing side effects.

Add tests that bad inputs to SCROLLX/SCROLLY are recoverable with :erract.

Add EVALTEST.SILENTLOADFROMTREEIFY.SYNTAXERROR
This is similar to EVALTEST.SILENTLOADFROMTREEIFY.THROWSERROR, expect it
exercies a different code path and causes the stopping_flag to be set to STOPPING when treeifying.