Merge branch 'master' of https://github.com/dae/anki
Merge branch 'master' of https://github.com/dae/anki
Merge branch 'master' of https://github.com/dae/anki
Merge branch 'master' of https://github.com/dae/anki
Merge branch 'master' of https://github.com/dae/anki
Merge branch 'master' of https://github.com/dae/anki
Merge branch 'master' of https://github.com/dae/anki
Merge branch 'master' of https://github.com/dae/anki
Merge branch 'master' of https://github.com/dae/anki
Merge branch 'master' of https://github.com/dae/anki
Merge branch 'master' of https://github.com/dae/anki
Merge branch 'master' of https://github.com/dae/anki
Merge branch 'master' of https://github.com/dae/anki
fix error handling for selecting invalid file type

(The error was never appearing because the test was missing quotation
marks.)
check that save to desktop was successful before showing message
add unchanged count to import log
more helpful error message for corrupt collection package
prevent nesting things under filtered decks

This change keeps drag-and-drop behavior the same except for displaying
an error if an otherwise acceptable move would nest anything underneath
a filtered deck.
only display "added duplicate" message once

Even if there are several (duplicate) notes in the collection that
match, only send the message once to avoid making it look like multiple
dupes have been added.
add "export" button to deck menus