[packman] Change of repository layout

[Tomáš Chvátal]

Hello guys,

I noticed that from time to time we are prone to diverge from the
buildtargets. Eg we have too new gstreamer/etc.

Wouldn't it be better to have repositories set up in a way:

Essentials/Factory with only factory enabled
Essentials/13.1 with only 13.1 enabled
...

Where all the external links for obs would link to the package from the
specified repo and not to factory. This would solve the collisions people
sometimes have when using packman.

For the internal links we could even have the packages to be links to
/Factory or we could go for some maintenance approach where old releases
would ie keep old ffmpeg and so on.

I am not sure if this approach is not using more resources :(

Cheers

Tom