Add save/restore state to allow multiple calls to parse

[shadowspawn]

Pull Request

Problem

People may not realise parse should only be called once, and discover by trial and error.

See: #438 #1565 #1819 #1829 #1916 #2036 #2246 #2247 #2263

Solution

I thought it was going to be hard and messy to save/restore state and not worth it, but turned out fairly straightforward! Fingers crossed.

When storeOptionsAsProperties: false allow multiple calls to parse by storing and resetting the state. This is done in a lazy way, so a wide or deep hierarchy of subcommands does not need to save state on whole tree.

When storeOptionsAsProperties: true then throw on the second call to parse.

Not planning to support multiple calls to .parseOptions() as little used for direct calls, but could do that by moving the implementation into a private routine and call ._prepareForParse() in public routine.

ChangeLog

• support multiple calls to .parse() with default settings
• throw on multiple calls to .parse() if storeOptionsAsProperties: true
• add .saveStateBeforeParse() and .restoreStateBeforeParse() for use by subclasses

[shadowspawn]

Comments welcome on routine naming or more interesting cases to add to unit tests.

[shadowspawn]

Released in Commander v13.0.0