mid testing to understand imaginary parts in FFTS of correlation funcrions
(#430)
modified correlatednoise.py to use hermitian trick on (now forced) even-sized arrays.  Does not yet seem to guarantee that the PS is negative in all cases, think this may be a physical effect due to noisy estimates.  Could still be a bug, so will try forcing odd as Mike suggested.
(#430)
merged in Mike's branch of #430, my changes now on #430test, kept all Mike's changes on this branch