Patch v0.99.12

Fixed a bug where the abandoned mine could not be clicked.
Resolved an issue where empty save files were incorrectly displayed as deleted.
Fixed a bug where summoned caravans would disappear after loading a save file.
Fixed an issue in the map editor where invalid saves were allowed.
Fixed a bug in Level 4-3 where the monster wave in June was incorrect.
Resolved an issue where monster spawn points were abnormal after loading a save file.