add {{Subdeck}} special field

If the deck is a several levels into a tree, it can be needlessly
verbose to list them.
Merge branch 'master' of https://github.com/dae/anki
catch more invalid zip file errors
Merge branch 'master' of https://github.com/dae/anki
fix inconsistency in default note type names

The value used internally was changed at some point and the text that
was added to the GUI was not.
be explicit about modSchema()'s check flag

- remove gui code that adds exceptions for syncing
- use check=False for all syncing and upgrade code
cont should be checked befoer any further processing