Merge branch 'terencehill/weapon_panel_retry' into 'master'

Weapons panel improvements

I've taken into account sev's feedback at !106 and after lots of tests I came up with something good, I think.

To sum it up the changes:
* weapons are now sorted either vertically (more rows) or horizontally (more columns) (not just vertically as before)
* all weapons layout: more symmetrical distribution, icons are now as big as possible
* only owned layout: prefer stretched layouts (like in sev's branch) but avoid too much stretched layouts where item aspect ratio gets altered

See merge request !110