Minimap as HUD element with API control

Features:
 * Define Minimap available modes (surface/radar, scale) from Lua, using player:set_minimap_modes()
 * New HUD elements for displaying minimap with custom size and placing
 * New minimap mode for displaying a texture instead of the map

src/script/lua_api/l_object.h

@@ -377,4 +377,7 @@ private:
 
 	// send_mapblock(pos)
 	static int l_send_mapblock(lua_State *L);
+
+	// set_minimap_modes(self, modes, wanted_mode)
+	static int l_set_minimap_modes(lua_State *L);
 };