Trig and Math functions added
We added the COS, SIN, TAN, ACS, ASN, ATN trigonometric functions along with the LOG, EXP and SQR math functions to the system. In order to simplify the coding we placed all these functions in a common module called nf_trig.c rather than separate modules for each function which seemed a waste given each function was basically identical and only a few lines long.
