Is your feature request related to a problem? Please describe.

As the primary contributor to a project, I'd like a means to define default values for custom properties to save needing to type them in every time.

Describe the solution you'd like

Make it so that if you have a config file like:

# .changie.yamlenvPrefix:CHANGIE_custom:-key:Authortype:string

Then having an env var calledCHANGIE_CUSTOM_AUTHOR defined would be applied the same as if you did--custom Author="George" when doingchangie new. This'll enable a way to have localized defaults for me without affecting other user's workflow.

Describe alternatives you've considered
Just doing something like:

custom:-key:Authortype:stringdefault:George

would be another option, but is a lot less flexible than the ENV var approach. Also could lead to confusion when other people go to dochangie new as well.

Additional context

Discussed a bit in#800.