Zirpl CalcEngine parses and evaluates string-based mathematical formulas.

NOTE: This is not an original Zirpl work. It is a port of CalcEngine found at: http://www.codeproject.com/Articles/246374/A-Calculation-Engine-for-NET to a Portable .Net library (PCL) so that it can be used in the widest variety of projects. Original source code can be found at that website. A few items have been altered so the code will compile in a PCL and a few items have been added.