Get menu background image from selected game
Filter worlds by selected game
games/minimal: Add menu/background.png and menu/icon.png
Pre-select current game in world creation dialog
Switch menu to game selected in world creation dialog
Show game name instead of game ID of selected game
Use DIR_DELIM instead of / in file paths
Server: force block send of pointed_pos_under after predicted node place
Predict wallmounted param2 during node placement prediction.

Also clean up the_game a bit: move node placement prediction to a
separate function.
Don't predict placement of nodes if they would replace a non buildable_to node
Optional dependencies and properly handle mod name conflicts again