Convert latex formula into MathObject compatible.

MathObject is Webwork's representation of a math equation/formula.
MathObject takes some kind of ASCII math like syntax for formulas. So I
had to convert the latex formula into ascii math for use in Webwork.

This, luckily, wasn't as vast an undertaking as it could be, since
Blackboard's calculated formula is restrictive in what it considers
valid.

You can't use Greek letters as variables, only alphabetical ones. And
the number of functions supported (sin, cos, tan, etc) is small.

Warning! Equations containing round, floor, and ceiling will NOT work
because they weren't converted by the MathML converter I used.

The most complicated part of the formula parser is the part responsible
for prepending $ to variables. Simple solutions are confused by sin, cos,
tan, etc since they contain characters that may be used as variables.
The next simplest solution I could think of was to just remove the sin,
cos, tan, etc functions before subsituting the variables back in.