spacetelescope/drizzlepac: Drizzlepac v3.4.0

What's Changed This major release adds support for multi-visit mosaic (MVM) processing, in addition to including numerous revisions to try to align more datasets successfully to GAIA during pipeline and single-visit mosaic (SVM) processing. Multi-visit mosaics (MVM) introduce the concept of SkyCells with new code added to define them. SkyCells are subarrays of pre-defined tangent planes spaced regularly on the sky as standardized definitions of mosaics to be created from all HST observations taken of each part of the sky. New features added in this version include: Support for creating MVMs as generated by the 'drizzlepac/hapmultisequencer.py' module or using the new command-line task runmultihap. Tools for generating cutouts of MVM products found in the drizzlepac/haputils/hapcut_utils.py module. The most significant revisions and bug fixes that affect output products of this version of the code include: Detect extension name from WFPC2 flat-field files. [#1193] Refactored the build system to be PEP-517 ad PEP-518 compliant. [#1244] Fixed a bug in the drizzle algorithm due to which input pixels with zero weights may still contribute to the output image. [#1222] Added Sphinx documentation describing tools used for working with MVM products. [#1144, #1150] Changed names of "ISO" columns in Segmentation catalog to be unique [#1155] Add WCS keyword values to catalog metadata [#1160] Enforced a minimum number of cross-matches for alignment to be 4 sources [#1187, #1218] Revised 2D background determination for smaller detectors to improve source detection during alignment. [#1187] Create empty catalogs when exposures are effectively blank. [#1199] Cut processing time from days to minutes for exposures of crowded fields of faint sources or fields dominated by a single large extended source. [#1198] Report correct value of NMATCHES keyword for number of sources actually used in alignment fit to GAIA. [#1217] Prevent older distortion models from overriding new distortion models when performing a posteriori alignment to GAIA. [#1220] Add explicit dependency on spherical-geometry package. [#1232] Update how make_poller_files.py generates visit numbers. [#1221] Insure both FLT and FLC headers have same a posteriori fit keywords. [#1238] MVM: Make tool to quantify quality of GAIA alignment generic for general use. [#1241] Fix logic to not align grism data in standard pipeline. [#1243] Remove nictools as a dependency for this package. [#1245] RickerWavelet Kernel for SBC to separate crowded PSFS needs to have dimensions which are odd [#1246] Refine headers for filter and total products to allow keywords like IPPPSSOO and ASN_ID which only apply to single exposures (or data from the same ASN) to be removed from SVM filter and total drizzle products and from MVM layers drizzle products [#1249] Remove logic from align that related to checking for alignment results in align.py when it was not necessary so that more data can successfully align to GAIA. [#1250] Add support for using astropy 5.0. [#1280] Full Changelog: https://github.com/spacetelescope/drizzlepac/compare/3.3.1...3.4.