[WIP]Handle unsupported

[dpgrote]

This is a proposal for a mechanism to handle unsupported arguments and values.

For unsupported arguments, this assumes that any that are checked have a default value of None. Note that not all arguments have that as a default value, but this method covers most arguments.

[s9105947]

While adding such warnings: This would be the prime oppurtunity to add a deprecation warning feature with a similar syntax. This will surely be needed at some point in the future. (Or should we postpone this until needed?)

[ax3l]

While adding such warnings: This would be the prime oppurtunity to add a deprecation warning feature with a similar syntax. This will surely be needed at some point in the future. (Or should we postpone this until needed?)

Good idea. Do you want to add that in a follow-up PR?

[dpgrote]

This was closed because it has unrelated commits, and is replaced by PR #67