Add a setting for selection copying to result in markdown that tries to keep the same format

[wheelercj]

The setting "when creating markdown of a selection, ____" should have an option called "try to keep the same format". This will allow us to eventually add support for copying tables as markdown. Markdown renderers typically do not allow tables to be in block quotes.

For context, that setting's current options are "create a block quote and a page title link", "create a link with the selected text as the title", and "create a link with the page title as the link title".

Something to think about: should the copied markdown also have a page title link at the end? Maybe there should be two new settings so the user can choose.

It would probably be good to rename the setting's code name from linkFormat to selectionFormat.