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Use SQL prepared statement for insertion

When creating a new manga with a name containing a quote (') it would
fail. No message was shown to indicate it had failed and the manga was
not added.

This was caused by not quoting the quote in the SQL. All SQL queries
should use prepared statements in order to make no mistakes quoting
quotes and other things.
Show alert when adding a manga fails

In the future this should be expanded to include why adding it failed.
Use (real) prepared statements for all db actions

Prepared statements were already being used, but wrong. Instead of
creating a string with the right information the SQL should contain
parameters which should be bound by other functions.
Show some messages for errors

When certain actions can't be completed messages are now shown.
Update changelog