Command-line options need to be parsed twice

On qreator/__init__.py, main() function we parse the options after having loaded the plugins. We do this so that plugin-specific options can be added.

However, that poses a problem for options that need to be read before plugins are loaded, such as -v (verbose). This means that logging will not be set up for any code before we load the plugins.

We should read the options twice:

- Once at the start of main() to get the generic options
- Once after plugins have been loaded to append the plugin-specific options