Class with trigonometric, inv. trigonometric, hyperbolic and inv. hyperbolic functions

The static methods implement safe versions of the functions, trying to avoid under- or
overflows, testing if key values are close to zero. More exactly if they are within
[-epsilon, epsilon], where epsilon = 1E-15.

This is code based on [PEAR's Math_TrigOp](,
and compatible with PHP 5.3+ and PEAR2.