Add /emergeblocks command and core.emerge_area() Lua API

builtin/game/misc.lua

@@ -109,6 +109,25 @@ function core.get_connected_players()
 	return temp_table
 end
 
+-- Returns two position vectors representing a box of `radius` in each
+-- direction centered around the player corresponding to `player_name`
+function core.get_player_radius_area(player_name, radius)
+	local player = core.get_player_by_name(player_name)
+	if player == nil then
+		return nil
+	end
+
+	local p1 = player:getpos()
+	local p2 = p1
+
+	if radius then
+		p1 = vector.subtract(p1, radius)
+		p2 = vector.add(p2, radius)
+	end
+
+	return p1, p2
+end
+
 function core.hash_node_position(pos)
 	return (pos.z+32768)*65536*65536 + (pos.y+32768)*65536 + pos.x+32768
 end