This mod add `setblock` and `place` command

## Commands

### /setblock x y z modname:foobar_node & /place x y z modname:foobar_node
Place a block at x,y,z (setblock call `minetest.set_node`, and place call `minetest.place_node`)

### /setblock_heremodname:foobar_node & /place_here modname:foobar_node
Place a block at your pos (setblock call `minetest.set_node`, and place call `minetest.place_node`)