Add gmtools to utils, add splash to controlfolder

[JeodC]

Usage:
Patchscripts reference:

# Exports
export DATADIR="$GAMEDIR/assets"
export TMPDIR="$GAMEDIR/tmp"
export DATAFILE="my_game.port"
export SDL_GAMECONTROLLERCONFIG="$sdl_controllerconfig"

export LD_LIBRARY_PATH="$controlfolder/utils/gmtools/libs:$LD_LIBRARY_PATH"
export TOOLDIR="$controlfolder/utils/gmtools"
export PATH="$controlfolder/utils/gmtools:$PATH"

Splash reference
$ESUDO $controlfolder/splash "$GAMEDIR/splash.png" <milliseconds>

To be reviewed + tested before merging

[JeodC]

Tested and verified with Isles of Sea and Sea refactor: https://github.com/JeodC/PortMaster-IslesofSeaandSky

[kloptops]

Needs a license/build instructions added for this.

The file BUILDING_STUFF.md is where i document it.

We also need at minimum x86_64 version.