This adds a new button to the Advanced prefs to migrate the data directory to
$HOME/Zotero. The button only appears if the data directory is set to the
default location within a profile directory (including the other program from
the one running, even though that's technically stored as a custom data
directory).
On Mac/Linux, directories within the data directory are moved with /bin/mv. On
Windows, or if that fails, they're copied recursively using OS.File.move()
(which annoyingly doesn't reliably support directory moving). The former should
be instantaneous on most systems (unless the data directory or 'storage' were
on a different filesystem from $HOME).
If the database fails to transfer, migration fails and the data directory
setting remains on the old directory. If the database transfers but other files
fail, the data directory setting is updated. In both cases, the user is
encouraged to migrate remaining files manually with a button that reveals the
directories and quits the program.
This isn't yet tested on Linux or Windows, and migration isn't yet suggested
automatically.
Adds Zotero.File.reveal(), Zotero.File.directoryIsEmpty(), and
Zotero.File.moveDirectory().
