Use language system wherever possible (part 1).
Merge remote-tracking branch 'origin/language-enhancements' with 'upstream/refactor' into language-enhancements-two

Conflicts:
	entities/entities/drug/init.lua
	gamemode/modules/events/sh_zombie.lua
	gamemode/server/main.lua
	gamemode/server/player.lua
	gamemode/shared/entity.lua
Use language system wherever possible (part 2).
Now let's clean up the trail of errors I left behind.
Merge remote-tracking branch 'origin/language-enhancements-two' with 'upstream/refactor' into language-improvements

Conflicts:
	gamemode/modules/doorsystem/sv_doors.lua
	gamemode/shared/commands.lua
Merge pull request #816 from Bo98/language-improvements

(Refactor branch) Made use of the language system wherever possible