Tile map

- Fix get iso position issue with irregular object shape.
- Improve on portal system.
- Portal and spawn point now same same object layer and are randomed
from a list    of objects.
- Fix portal placement issue/offset
Merge remote-tracking branch 'origin/master'

Conflicts:
	Classes/AppDelegate.cpp
	Classes/GameScene.cpp
	Classes/Helper.cpp
	Classes/Helper.h