FlashFork: ability to copy/duplicate/fork a deck and its note types (record types)

[pconstrictor]

Menu option: Duplicate current deck.

0. Ask the user, "Are you sure?" and Indicate the name of the deck that will be copied.
1. For each note type (record type) used by the current deck (Deck A), ask the user whether to fork the note type as well. Once the user has made decisions for all note types, create new types as needed, by copying the existing ones.
2. Create a new deck (Deck A2) with a new ID. Initial name: same name, plus the word "copy" or a number at the end
3. For each card in Deck A:
   a) skip this card if it has the same note as a previous one.
   b) Find its note and create a new note in Deck B with the same content but a new ID
   c) Set the new note's type to whatever was chosen in step 1.
   d) generate a set of flashcards for the new note and make sure their deck is set to the target deck.

See also: issue #9, #14

[pconstrictor]

Done. Fully implemented except that step 2 never provides "copy". And step 3b only copies the card/note's "main data"; not sure if there's other metadata that matters, such as card history.

Example of usage:

You've received a template deck (deck 'T') with desirable fields, card templates, and sample records that include stock images. You want to fill them out for language A during the course but may want to use the same template later for language B. And you might want to import another student's language C deck to help them or learn from them. Here's what to do:

• Back up deck T (via File Export to .apkg)
• Get the latest FlashGrid
• Make a copy (under Tools) of Deck T and choose Clone All for its note types. (This way, the two decks' settings won't conflict or overwrite each other if they diverge but later get imported onto the same computer. Only choose Share All when you're sure they shouldn't diverge.)
• Back up again, just in case.
• Rename the new Deck and its note types appropriately.