This patch aims at reducing the number of copies for obejcts that could
be referenced rather than copied, because they're not modified during
the computation.
The CLI module was lacking unit test coverage and showed some severe
coding style violations, which this patch addresses.
In addition, all uses of qCritical() with untranslatble raw char*
sequences were removed in favor of proper locale strings. These are
written to STDERR through QTextStreams and support output
redirection for testing purposes. With this change, error messages don't
depend on the global Qt logging settings and targets anymore and go
directly to the terminal or into a file if needed.
This patch also fixes a bug discovered during unit test development,
where the extract command would just dump the raw XML contents without
decrypting embedded Salsa20-protected values first, making the XML
export mostly useless, since passwords are scrambled.
Lastly, all CLI commands received a dedicated -h/--help option.
