Summary of changes:
* Extract function for creating password generator from options into
`Generate` command. This function is now reused in `Add` and `Edit`
commands.
* Updated manpage with missing password generation options.
* Updated manpage with missing longer forms of password generation options.
* Added unit tests for new password generation options in `Add` and
`Edit`.
* Handle case when `-g` and `-p` options are used at the same time.
This PR adds password generation functionalities while reducing
code duplication, but at the cost of 2 small breaking changes:
* The password generation option for `Add` and `Edit` for specifying
password length is now `-L` instead of `-l`, to not clash with the
`-l --lower` option.
* The `-u` shorthand for the `--upper` option has to be removed, to not
clash with the `-u --username` option.
* Add -U variant for uppercase.
* Empty destructors are replaced with default destructors
* A few loop variables made into const references to avoid copies
* Add missing `override` spec for some `Command::execute` methods
This PR cleans up the `Command` classes in the CLI, introducing a
`DatabaseCommand` class for the commands operating on a database,
and a `getCommandLineParser` command to centralize the arguments
parsing and validation.
The opening of the database based on the CLI arguments and options
is now centralized in `DatabaseCommand.execute`, making it easy to
add new database opening features (like YubiKey support for the CLI).
Also a couple of bugs fixed:
* `Create` was still using `stdout` for some error messages.
* `Diceware` and `Generate` were not validating that the word count was an integer.
* `Diceware` was also using `stdout` for some error messages.
