documentation updates
Add SecondaryObscuration and RectangleAperture; misc other edits
add configuration saving using astropy.config package
add autosave_fftw_settings
added WavefrontError base class skeleton.
added fftw wisdom saving; fftw speed comparison tests utility function
add autoreload of saved fftw wisdom
autosave fftw wisdom; add ability to save padded intermediate wavefronts
documentation URL update
documentation update