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

Space Invasion: Fix missing arg in math.min

Space Invasion: Fix possibility to go over shield limit with param

Space Invasion: Fix minor visual glitches of shield

Update changelog WRT sounds

Remove redundant PoisonCough/PoisonMoan sound files

Separate Yoohoo.ogg into "Yoohoo" voice and kiss sound Sound has been separated with mp3splt, so no quality loss

Poison taunts: Fall back to Default voice if missing

Update changelog WRT translations

Don't include Arabic in release (RTL support is broken)

Add yuenfu to credits for Chinese translation

Update Chinese (zh_CN, zh_TW) translation: Frontend and engine

Add Chinese (zh_TW) translation for campaigns and missions

SimpleMission: Fix incorrect documentation for distGearGear and distGearPos

SimpleMission: Fix Lua error spam when a goal fails

Add integerSqrt and integerHypotenuse to Utils lib

Select appropriate schemes when taking room control (bug #461)