Merge pull request #669 from stefanbeller/master

Formal maintenance
Only clear intermap teleport flag when the destination name is empty

This fixes a bug where the player would get stuck on maps/spawn.txt when
trying to load a game with an invalid map.
Merge pull request #671 from dorkster/missing_data

Only clear intermap teleport flag when the destination name is empty
Fix memory leaks
Merge pull request #673 from stefanbeller/memleaks

Fix memory leaks
Fix multiple enemy spawns on one tile