Reduce expense of Lanczos filter by using an fast approximate sin function.
IBA resize optimization

Improve the performance of IBA::resize when using separable filters with
large support (e.g., resizing an 8k image to 512 using Lanczos improves
resize performance by 25-50%). The refactor of IBA::resize is primarily
to hoist all the redundant calls to filter evaluation and normalization
out of the inner loops -- for each (x,y) in the output, the x filter
taps can be computed once (rather than once for each y tap), and the y
filter taps only need to be computed and normalized once for each
scanline in the image.