Allow for multiplication and division of conditions that return numbers.

Allow for multiplication and division of conditions that return numbers.

All "numbers" are actually linear functions of the form:

	f(t) = a + (t - b)*c.

Multiplication and division of linear functions does not yield a linear
function in the general case, but the resulting function can be
approximated with a first order Taylor series expansion around the current
time point.

git-svn-id: svn://svn.curseforge.net/wow/ovale/mainline/trunk@1058 d5049fe3-3747-40f7-a4b5-f36d6801af5f