-Removed temp variable from (single) assignments
-Fixed multi self assignment (a, b = b, a)
-Added unary operators: UAdd, USub (only for literals)
-Added math functions: ceil, fabs, floor, exp, pow, sqrt, acos, asin, atan, atan2, cos, hypot, sin, tan, acosh, asinh, atanh, cosh, sinh, tanh
-Added math constants: pi, e
Merge branch 'master' of https://github.com/undefx/vecpy