Calculator

The calculator handles basic arithmetic expressions with a few specialties:

• The calculator does not handle locale specific number formating. It always uses the "." character for the decimal point, even if the locale says to use "," instead.
• To clear the print, simply evaluate an empty expression.
• Two non-standard operators are available: +% and -% for conveniently adding or subtracting a percentage from a given value. For example 100 -% 2 will give 98 as a result.