FMSLogo Code

Avoid multiple calls to GetScreenHorizontalScrollPosition/GetScreenVerticalScrollPosition
gprof says that this takes a long time, but I don't know if that's trustworthy.
Even if not, calling those methods half as many times isn't bad.

Don't use a back buffer was used when drawing regular turtles.
This was a regression that was accidently introduced when adding a back buffer for all bitmapped turtles (instead of just sprites).
This regression caused a 200% slowdown in the squiral benchmark.

It doesn't make sense to use a back buffer when drawing normal turtles, as there is other logic to draw them directly to the screen as the turtle is moved, bypassing any back buffer.

Add missing header files to fix build breaks when compiling without a precompiled header.

Add benchmark results for FMSLogo 8.3.0

Update expected test results based on second 8.3.0 test pass (after fixing a test bug in dll.lgo)

Update results based on the 8.3.0 test pass

Fix a test bug that caused a crash (invalid memory read)
Also remove repeated test cases.

Update with the results from the 8.3.0 test pass

Increment the version to 8.3.0 to prepare for a formal release

Ban "non-negative" and "non-zero"
The forms without hypens are now preferred in technical literature.
See "Mathematical Writing" by Donald Knuth.