* Python 3.7 support (https://sf.net/p/pymol/bugs/197/)
* enable align with alt-codes
- allow matching of non-alt-code to alt-code atoms in alignments
- swap sorting priority of 'name' and 'alt' identifiers
- sort empty 'alt' before non-empty 'alt'
* flags 6 and 7 for protein and nucleic acid
* mmCIF: read _atom_site.pdbx_formal_charge
* improve coordinate loading from mmcif chem_comp files
- ignore columns with all ? (missing) values
- select columns with "chem_comp_cartn_use" setting
* fix h_add: skip missing coordinates
* experimental MMTF load support
* map export in CCP4 format
* SDF V3000 import/export support
* refactor molecular file formats export: Unified handling of PDB, PQR, mmCIF, MOL2, SDF, XYZ, MAE
* PLY geometry import (as CGO)
* new command: unset_deep
* new setting: cartoon_all_alt: Create cartoon for every alt code
* stick_h_scale: default=1.0 (was: 0.4) but remove dependency on negative stick_radius
* auto_show_classified: Visualize small (< 50 atoms) polymer classified molecules like organic
* bymol selection operator: ignore zero-order bonds
* menu: isomesh/surface negative color
* improve alignment of residues with unknown resn (e.g. ligands):
give a match score of 5 to perfect matches of unknown residue codes.
Previously, those got match score -1.
* remove broken and obsolete "PMO" file support
* use "label_digits" setting with "label" command
* do not resize window when loading a session file
* fix ignored SCALE w/ identity rotation (e.g. 1WAP)
* fix "scene auto, clear" (Scene > Delete)
* new setting: pick_shading: do flat shading for programmable image color analysis
* experimental cmd.raw_image_callback: post cmd.draw() callback
* ignore SCALEn if CRYST1 is 1x1x1 or invalid
* new/refactored API functions for accessing coordinates and maps as numpy arrays
* new API function: cmd.set_state_order
* Session file (PSE) support for callback objects
* fix/silence many compiler warnings
* fix bg_rgb_top/bg_rgb_bottom side effects
* revert "fix setting surface_circumscribe"
* delete some obsolete files
