Updated demo to version 0.7

Version 0.7 changes:

- Fog/smoke breaking line of sight.
- A new spell to create mist, which allows sneaking around enemies.
- A ton more fixes to wall cutting graphics.
- Better detonate spell's icon.
- Fixed bug with AI player's units activating triggers intended for human player only.
- Fixed update of tiles inside fog of war.
- Minor optimization to tileset loading.
- Fixed burning of objects under the flame and burning platform objects, so they get properly replaced with ash and units on top of them fall down into flame.
- Fixed unit transparency, so thin objects, like obelisks near portal and windows, wont block vision.