Release 1.5.0

The emphasis of this release is making it easy to select exactly what references should be included in the analysis, and also to output counts of references by type (e.g., branches vs. tags vs. pull request heads).

What's new:

• Allow several options to be set via gitconfig:
  • sizer.jsonVersion
  • sizer.threshold
  • sizer.names
  • sizer.progress
• Add more reference selection options:
  • --no-branches (the opposite of --branches)
  • --no-tags (the opposite of --tags)
  • --no-remotes (the opposite of --remotes)
  • --notes/--no-notes
  • --stash/--no-stash
• Allow references to be selected by prefix or by regular expression:
  • --include=PREFIX, --exclude=PREFIX
  • --include=/REGEXP/, --exclude=/REGEXP/
• Make it possible to define groups of references via gitconfig:
  • refgroup.REFGROUP.name=NAME
  • refgroup.REFGROUP.include=PREFIX
  • refgroup.REFGROUP.includeRegexp=REGEXP
  • refgroup.REFGROUP.exclude=PREFIX
  • refgroup.REFGROUP.excludeRegexp=REGEXP
• Make it possible to include/exclude references by refgroup:
  • --include=@REFGROUP, --exclude=@REFGROUP
• Create some predefined refgroups: branches, tags, remotes, pulls, changes, notes, and stash.
• Include, in the output, the numbers of references in each defined refgroup, including the predefined refgroups like branches and tags.

Internal changes:

• Use a new pipe package for managing command pipelines. This fixes some error-handling paths.
• Set up an action to run a linter over the code.
• Clean up a bunch of linter-reported warnings.
• Set up automated testing under Windows.
• Build with the Go 1.17.3 toolchain.