Fast Incomplete Gamma and Hypergeometric functions now handle symbolic input

Previously these functions blocked symbolic input as they were designed to speed up floating-point. It particularly convenient for gammaincq to handle symbolics as it does additional things.

New private function sym2str to handle fast conversions.

More testing should be performed. Documentations still needs to be updated.

gammaincq also updated for R2014b - it looks like the symobj::map catch function is no longer available.

Signed-off-by: Andrew D. Horchler <adh9@case.edu>