Add a new menu option to the main window (only visible when built with
the sqlcipher option enabled) which opens a dialog asking for new
encryption settings. These are then applied to a new database to which
all contents of the current one are exported. The old database is then
replaced by the new one.
This adds support for encrypting plaintext databases, decrypting
encrypted databases and changing the password or other settings of
encrypted databases.
If this turns out to work well enough we have functional SQLCipher
encryption support with only details missing.
Fix the sqlcipher build option in the qmake project to actually enable
the SQLCipher support.
Add a new dialog called CipherDialog which is used to ask the user for
the password and other encryption details instead of using standard Qt
input dialogs.
