Build 991247

-Changed level previews to JPGs as PNGs can exceed steams 1Meg limit
-fixed issue where dragging a block of tiles could result in some being off the map causing some errors. (they can still be off the map incase you want to drag them on again.. although may change this, but off map tiles are now accounted for).
-fixed issue to do with linking moving platforms, under certain circumstances could lock up the game.
-fixed some cannon issues
-fixed issue to do with some pickups re-spawning and falling such as potion
-allowed visibility to be set before sharing.
-allowed entering of Description and change notes before sharing
-fixed an issue with re-sharing multi level maps