Changed parser back to always use RTL crushing.
Changed parser back to always use RTL crushing.

This was because an expression like pi*r**2 was parsing as (pi*r)**2: LTR
crushing completely broke precedence.

Need to figure out how to solve the issue of a-b-c currently being parsed as
a-(b-c) when it *should* be (a-b)-c.

DanielKeep/MathEval