pycalver

New gitlab #7: New style patterns, to be in line with CalVer.org
- Better support for week numbering.
- Better support for optional parts.
- New: Start BUILD parts at 1000 to avoid leading zero truncation.
- New: Add INC0 (0-based) and INC1 (1-based) parts that do auto increment and rollover.
- New: MAJOR/MINOR/PATCH/INC will roll over when a date part changes to their left.
New gitlab #2: Added grep subcommand to find and debug patterns.
New: Added better error messages to debug regular expressions.
New gitlab #10: --pin-date to keep date parts unchanged, and only increment non-date parts.
New gitlab #9: Make commit message configurable.
New: Added --release-num to increment the alphaN/betaN/a0/b0/etc. release number
New: Added --date=<iso-date> parameter to set explicit date (instead of current date).
Fix gitlab #12: Error sorting non-lexical version tags (e.g. semver).
Fix gitlab #11: Show regexp when --verbose is used.
Fix gitlab #8: Push now also pushes HEAD (used to only push the tag).
Fix: Disallow --release=dev which has different semantics than other release tags.
Fix: Entries in file_patterns were ignored if there were multiple for the same file.
Switch main repo from gitlab to github.

v201907.0036

Fix: Don't use git/hg command if commit=False is configured (thanks @valentin87)

Fix gitlab#6: Add parts {month_short}, {dom_short}, {doy_short}.
Fix gitlab#5: Better warning when using bump with semver (one of --major/--minor/--patch is required)
Fix gitlab#4: Make {release} part optional, so that versions generated by --release=final are parsed.