Translate to Numpy

[mhucka]

Some subset of mathematical expressions could be converted if they could be transformed into a simpler form that is compatible with what can be expressed in core SBML. For example, some simple uses of arrays could be converted, but we need to re-express the constructs to avoid the use of arrays. This would require recognizing when arrays are intended versus when they are not, which would be complicated. However, if we translate the expressions into equivalent Numpy expressions, then we can manipulate them using Numpy operations.