[WIP] Adding evaluation for arguments containing k*pi

This PR essentially tries to add the functionality from certik's [trig version](https://github.com/certik/sympy/blob/trig/t.py) to the current csympy project.
The following things have been added:
*  sine_table lookup
*  Updated get_pi_shift to recognize args of form `n*pi/12`
*  Updated sin to use sine_table before creating an object.

Work to be completed:
* Currently `isqrt` is used in sine_table. we've to shift it to irrational perhaps. A new class of irrational and subsequently reals under Number?
* Updated get_pi_shift to recognize `x + n*pi/12` where `n` is integer
* Add rules so that all other trignometric functions use lookup table before creating an object.