Use Minetest as a debugger

[GreenXenith]

Maybe not an actual full-blown debugger, but it would be handy to be able to launch Minetest from the development environment.

The --go switch with the Minetest executable should be good enough.

Some things to consider supporting:

• Specify the executable path (required)
• Use a temporary world or existing world
• If developing a mod, specify a game id (also provide a setting for default game id)
• Allow specifying a minetest.conf