1.1.0

• Added support for functions with zero or >1 arguments.
• Added new functions: pi, ceil, floor, gamma, hypot, max, min, modulo, mod, and sign.
• Added if function. Syntax is if(expression, value if true, value if false), where false = 0.0 and true is any other real value.
• Now allowed to have variables with the same name as built in functions.
• Fixed a crash when parsing some expressions with syntax errors.
• Updates to the tests.