Minetest Gitinstall and Gitupdate scripts

The Minetest Gitinstall and Gitupdate scripts are simple scripts that automate obtaining latest Git version of Minetest game (from celeron55’ s GitHub repositories). Gitinstall installs the engine and the game into the “minetest” subdirectory of script working directory. Gitupdate should be placed in the existing Minetest engine Git repository and then running it will cause update of the engine and the game with recompilation of the engine if necessary.