Increase playerlimit

[elexis]

Currently the engine has an 8 player limit, but it could be entertaining to play with even more.

This is a non-trivial change as probably many data structures in C++ components rely on that limit and maps being designed for at most 8 players.

The performance shouldn't be affected significantly if the mapsize stays the same and the population limit is reduced proportionally. As of r17881 the network code already supports up to 24 clients without a noticeable performance impact.

[sanderd17]

This is certainly not a trivial task. Next to the many data structures that depend on the number of players (they aren't all limited to 8 players, but most are limited to some number between 8 and 16), there's also the GUI (setup screen, statistics screen, diplo screen, ...).

Having to create scenario and skirmish maps for more than 8 players is to be expected, but player placement on random maps is currently also only tested for 8 players. So all random maps should be retested.

And for every extra two players added, you need to add an extra team possible.

[elexis]

The GUI part shouldn't be that problematic, a good number of places have been changed already: r16975 r18104.

[Palaxin]

Regarding random maps: Perhaps we can implement a lower and higher limit for the available map sizes and the supported number of players? So not all existing maps have to be tested and edited...

[Palaxin]

I mean this limits would be specific to each map

[Imarok]

refs #3506

[elexis]

In 19840:

Group starting positions of players by team on the new random map sripts in Alpha 20 and 21, making them much more playable.
Use stronghold starting position style with 33% instead of 50% probability.

Differential Revision: ​https://code.wildfiregames.com/D664
Reviewed but not accepted by: bb (everything) and fatherbushido (Heaps permutations)
Catch: This must become more efficient if the playercount will be greater than 8, refs #4004.

[elexis]

Notice the feature would also be useful for 8 players + scripted enemies that aren't gaia (danubius, jebel barkal)