Split the generic "operator" node into "arithmetic" and "compare" nodes.

Split the generic "operator" node into "arithmetic" and "compare" nodes.

"Arithmetic" and "compare" nodes return different things when computed, so
split the computation into separate functions.

Modify the arithmetic computations so that the resulting values have an
origin of atTime, since all computations will ultimately be carried out at
t = atTime.

git-svn-id: svn://svn.curseforge.net/wow/ovale/mainline/trunk@1044 d5049fe3-3747-40f7-a4b5-f36d6801af5f