A shell calculatior based on the PowerCalc library

Current features:

• Interperet entered expression strings with the correct order of operation
• Easy access to common constants (well six of them this far)
• Create and combine functions containing unknown variables and evaluate them with different arguments
• Calculations return values with the correct order of significant digits !!!!BUG!!!!

Planed features:

• Graph drawing and perhaps some other types of analysis features
• Read values written on scientific notation
• Handle lists and sets of values

Bugs:

• Floats are sometimes printed with the wrong number of significant digits.
• Expressions called with arguments containing parenthesis enclosed ',' wont parse correctly