Merge

Prevent entering “/”, “\” and “:” in team and scheme names. The name of teams and schems is saved in the file name itself, so these characters would cause trouble as they are used in path names in Linux and Windows.

accept redirect messages

Escape HTML chars in stats screen

Frontend: Force plain text mode for many message windows

add redirect message

Merge alfadur's Opus commit and more

Fix some Qt<->SDL key mappings

Add lookup table for Hedgewars key IDs instead of generating IDs on the fly This makes sure the key IDs never change. Previous implementation abused SDL_GetScancodeName to generate the IDs programmatically, which was not reliable and explicitly adviced against in the SDL documentation <https://wiki.libsdl.org/SDL_GetScancodeName#Remarks>.

enable sdl_mixer opus support if possible

allow running plaintext and tls servers in parallel

Change init theme to Nature

Change theme to Nature if changing from background-only or hidden theme to a generated map type

Change color of fallback border/land texture in Planes theme to brown

Fix some ugly weirdness in fallback land/border textures of Blox/Eyes themes