Explore all rooms when entering Secret Lab

If you enter the Secret Lab from the title screen, all rooms will be
explored. However, if you enter the Secret Lab via the Secret Lab
entrance cutscene (epilogue), not all rooms will be explored, which is
inconsistent.

To do this, just do an SDL_memset() for the entersecretlab script
command.

desktop_version/src/Script.cpp

@@ -1515,6 +1515,7 @@ void scriptclass::run(void)
 			{
 				game.unlocknum(8);
 				game.insecretlab = true;
+				SDL_memset(map.explored, true, sizeof(map.explored));
 			}
 			else if (words[0] == "leavesecretlab")
 			{