Update v2.1

Mechanics changes and bug fixes

- Changed how healing and infection works
  * After infection, Building must be in light reach for 3 seconds, before being fully healed. Healing is reset, when Building is not in light.
  * If Building will not be healed in 60 seconds after getting infected, it will be consumed by the Plague (space around Element will be freed)
- Added simple particle around currently healed Building
- Fixed few cases, when player would receive Resources, even though he shouldn't
- Fixed problem with Buildings getting infected, when they shouldn't
- Fixed Obelisk structure, which would incorectly deduct Production timer
- Removed old restriction, which caused problem when Building was placed too far from Element, but close enough to be buildable