New Feature: Discord RPC integration

.drone.yml

libs/discord-rpc/win32-dynamic/include/discord_register.h

libs/discord-rpc/win32-dynamic/include/discord_rpc.h

libs/discord-rpc/win32-dynamic/lib/discord-rpc.lib

libs/discord-rpc/win64-dynamic/include/discord_register.h

libs/discord-rpc/win64-dynamic/include/discord_rpc.h

libs/discord-rpc/win64-dynamic/lib/discord-rpc.lib

src/CMakeLists.txt

src/Makefile

src/Makefile.d/features.mk

src/Makefile.d/win32.mk

src/Sourcefile

src/d_clisrv.c

src/d_clisrv.h

src/d_main.c

src/d_netcmd.c

src/d_netcmd.h

src/discord.c

src/discord.h

src/doomdef.h