pypeit/PypeIt: Version 1.9.0

Major Changes Reduction of Keck/DEIMOS now defaults to mosaics of red and blue detector pairs Package data is no longer distributed via PyPI. Instead, we use astropy's downloading/caching system as needed by the user Significant refactor of object finding and 2D extraction algorithms Added support for: VLT FORS2 600z grism VLT XShooter UVB arm Minor Changes/Improvements Default comb_id ordering matches the sorted file name in pypeit_setup Save output wavelength calibration from pypeit_identify to the cache for direct reuse in data reduction. The pypeit_identify GUI can now toggle between linear and log scaling of the arc spectrum flux. Dark subtraction now ignores any difference in exposure time, by default Added more flexible quicklook that can handle dithering. Bug fixes in local sky subtraction and extraction Fixed pypeit_setup issues due to bad LRIS headers. Fixed a bug in 2d coadding when objects were not being identified. Refactored 2d extraction. Minor enhancements to pypeit_identify GUI Refactoring of pypeit_show_wvcalib GUI Instrument-specific Changes/Improvements Improve Keck/KCWI automatic frame typing. Added wavelength templates for Keck/MOSFIRE (OH and arc lines) bok_bc 300 grating template Improved wavelength solution for Gemini-Nort E2V detector Keck/DEIMOS now uses gain/RN values measured periodically by WMKO Added enhancements and fixes for Keck lris red Mark4. Added code to better parse Gemini/GNIRS dither sequence