Feature: Add trigonometric functions.

[ZCG-coder]

Trigonometric functions can be done using reduction and trigonometric sequences.

Tasks:

• Add basic trigonometric functions ($\sin x$, $\cos x$, $\tan x$)
  • Add invalid value test.
• Add reciprocal functions ($\csc x$, $\sec x$, $\cot x$)
  • Add zero / invalid value test.
• Add inverse functions ($\arcsin x = \sin^{-1} x$, $\arccos x = \cos^{-1} x$, $\arctan x = \tan^{-1} x $)
  • Add zero / invalid value test.
• Add tests