Initial setup of the default directory

When you install Musescore, it stores files in a default location under Documents/Musescore3.
This is a good idea, but in certain circumstances, it creates a mess in existing directories.

For example, I own a bunch of scores stored into a complex Documents hierarchy -- which is also stored into an svn repository.
I would never want to store "automatic" directories into this svn nor I want to have to delete it on every machine I install Musescore on.

The only way to correct this is to:
-- launch Musescore -- which creates the famous default directory
-- navigate to Edit/Preferences
-- change every instance of "/home/mylogin/Documents/Musescore3" into something other
-- Apply and close Musescore
-- Open your filemanager
-- Destroy the directory /home/mylogin/Documents/Musescore3 -- or copy it's content into the new location(s).

It'll be nice if you only had the opportunity to specify this place the first time you launch Musescore.