Undoing commits r363 and r371 as it pertains to polylib.c, mathlib.c,

Undoing commits r363 and r371 as it pertains to polylib.c, mathlib.c,
and mathlib.h (the regression tests have not been removed).
Trunk is now restored to a state that it was in before I started
trying to fix the math accuracy errors in q3map2.  Commits r363 and
r371 were "correct" and did improve math accuracy significantly, but
unfortunately the underlying cause of math accuracy issues is something
else, which is being addressed in branch Rambetter-math-fix-experiments
currently.  I'm taking the BSD approach here, which is "we not going to
partially fix the problem.  it's all or nothing".  Otherwise it's just
too risky in my opinion.  I don't like playing Whack-A-Mole.

Someday, we might merge Rambetter-math-fix-experiments branch to trunk.
Sorry about all these needless commits to trunk.

git-svn-id: https://zerowing.idsoftware.com/svn/radiant/GtkRadiant/trunk@390 8a3a26a2-13c4-0310-b231-cf6edde360e5