Provide a way to separate out converted assets and static when passed to game via --data

[boombatower]

Currently --data expects the all assets, but for packaging (#94) and .desktop file (#81) it would make sense for static assets to be installed in /usr/share/openage and the converted ones to be in ~/openage/assets. Instead of having to duplicate all the static assets it would make sense to either symbolically link them all into ~/ which would be easier if static assets (instead of at root and /shaders) were in a single directory or provide another flag. Possibly just allow two directories?

--data=/usr/share/openage,~/.openage/assets

Where they are searched in order specified?

Otherwise, having an extra --data-converted that links directly to converted directory?

--data=/usr/share/openage
--data-converted=~/.openage/assets/converted

Or whatever directory structure is preferred for ~/...possibly just assets, but demonstrates the idea.

[mic-e]

See #86. IMO it would be best to specify the search order as userassets -> assets. The game would take an argument --assets=installed (/usr/share and ~/), --assets=dev (./assets and ./userassets). If the argument is not given, it will try to guess.

[franciscod]

rekt

fak-u-mic-e

(?)

[boombatower]

lol