CatacombGL 0.5.7 Beta

New in this release:

• Fix: prevent crash when taking certain exit portals, such as the exit portal that takes the player from The Warrens (level 14) to Access Floor (level 9) in Catacomb 3D. Reported by @DEA1HYT.
• Fix: in the folder selection window, hide inaccessible folders to prevent a crash when selecting such a folder.