Release v0.3.0

Configuration:

• For power users, a configuration API based on PEP 593 runtime annotations has been exposed in dcargs.conf.*.
• This includes: dcargs.conf.AvoidSubcommands, dcargs.conf.Fixed, dcargs.conf.FlagConversionOff, dcargs.conf.Positional, dcargs.conf.subcommand.
• The recommended approach for a "base configuration" pattern has changed to use these annotations. Introduced dcargs.extras.subcommand_type_from_defaults() to help with this.

Tab completion:

• Passing --dcargs-print-completion {bash/zsh/tcsh} to any dcargs.cli() script will now print an autocompletion script.

Some API changes:

• default_instance has been renamed default. The old name will still work, but will raise a warning.
• avoid_subparsers has been deprecated. It will still work, but will raise a warning.
• get_parser() has been removed.
• Deprecated serialization helpers to reduce maintenance burden.

Misc:

• --field_name can now be passed in instead of --field-name. The latter is still preferred and helptext is unchanged.