Campaing screen

[ottml]

Fixes #568 This is only a frist draft for further discussion

• [x] Support for lua file path different from map file path #1628
• [x] Campaign gui #1628
• [x] Lua file for campaign settings, including translation #1628
• [x] Campaign mission selection gui #1628
• [x] Add roman and continent campaign #1628
• [x] Disable map preview #1620
• [ ] Enable next mission lua support
• [ ] Storing of campaing progress in settings
• [ ] Update campaigns lua files with new functions

[Spikeone]

So, this is just my personal opinion: Although I do like the campaign screen itself, since it feels quite centered, But it requires lot's of clicking which feels quite a lot.

Therefor I do like the list version most. I can check what each campaign is about, can click continue, the mission selection screen is shown and I can continue by just clicking the mission. This feels great regarding the flow. Also when adding multiple campaigns this screen looks less lost and it makes more sense reading a longer description.

But I have to agree, that this still doesn't feel like the perfect solution, currently it feels as close as possible.

Idea: Maybe this view should also show headers like title, Author, Maps, Difficulty which are just strings but should be present in the rttr:AddCampaign. Also this screen shouldn't be the map selection screen (so the random map, ..., load game etc. buttons shouldn't be visible).

Everything else (except a "disable map preview") is looking pretty good to me!

I like it that way, honestly:

[ottml]

Not needed anymore is solved by #1628