Customize Loading-Progress

[AuderixDev]

I would like to customize the whole Splashscreen layout.
But I have problems with the progressbar. The progressbar is very subtle.
Can i somehow show the percentage of the progress and, maybe, show it more in the center of the screen?

As I understand the progress is filled with data from the uno-bootstrap.js.
Can I overwrite parts from it (e.g. initProgress)? If so, how can I do this?

[jeromelaban]

Thanks, let's track in #951.