cgame: preselect a map in server creation window, remember it

[illwieckz]

Preselect a map in server creation window, this means a newcomer has less actions to do to create a server when trying the game for the first time, and then remember the last started map.

[illwieckz]

I added a commit that forces the height of the levelshot. I forced 16:9 ratio. This is not too bad, even on old legacy maps that had 4:3 levelshots.

This prevents the server creation window size to change dynamically while scrolling maps, hence preventing the “Start” button to move up and down while scrolling map, and it would prevent a nasty map with a nasty 1:1000 levelshot to move the “Start” button off screen.

[slipher]

I don't have time to review or test, but I would ask to ensure that this does not cause a map pak to be loaded before opening the map menu.

[DolceTriade]

I don't have time to review or test, but I would ask to ensure that this does not cause a map pak to be loaded before opening the map menu.

This shouldn't do that