Add placeholders for transcendental functions in mpbq & mpq
Add more tests to interval
Reformat mpfp.h
Add transcendental functions to interval.h
Add constants(Pi, 1/2Pi, 2Pi) to double, float, and mpq
Add is_empty & set_empty to interval
Add transcendental functions to interval (still need to fill more...)
Add more operator overloadings to mpfp
Add constants and transcendental functions to mpfp