Added sin/cos/tan functions

Hi all, I've now added in sin/cos/tan functions into Pas 6502.  For now, they can only be used if their parameters resolve to numbers, but they are still useful for constant array for-loops, and where you need a sin/cos/tan value in your code as a number.

• sin(x, n) – returns n*sin(x*PI/128)
• cos(x, n) – returns n*cos(x*PI/128)
• tan(x, n) – returns n*tan(x*PI/128)

I've updated the array consts example to include a sin example 😊👍