Changes

Bit changing changes (#1104)

* Moving functions called inside loops to their own 2D subroutines. This is for performance, but is also BIT_CHANGING.

* Correct range of values to calculate for term_dp1_lhs

* Comments and cleanup

* Slight change to Skx_func, this is mathematically equivalent but BIT_CHANGING. This is faster on GPUs, and doesn't seem to have a signficiant impact on CPU performance.

* Introducing wp_coef and wp_coef_zt to reduce needed computations. This changes order of operations, so it is BIT_CHANGING.