modified Spectrum1D.from_fits() and added Spectrum1D.to_fits() to read and write into simple FITS files
minor typo fix
Merge remote-tracking branch 'upstream/master'
fixed minor sphinx bug - thanks matplotlib PR 1708!
https://github.com/matplotlib/matplotlib/pull/1708/files
Merge commit 'b6e929760e7cad67e97d59e8dc941be31011c21d' into input_output_revision
Merge commit '65415ed6a6ad2fba130d65f9d844fd6614acdc4b' into input_output_revision