Add visibility property in Drawable2D.[ci skip]
Use multi thread check Drawable2D visiblity.
Exposed allowed screen orientations (effective on iOS only currently) and the flush GPU setting as engine startup parameters.
Travis CI: API documentation update at 2014-03-27 22:49:42 UTC.
[ci package]
Fixed missing potion in NinjaSnowWar.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	Bin/Data/Models/NinjaSnowWar/Potion.mdl
	Source/Engine/LuaScript/pkgs/Graphics/Graphics.pkg
	Source/Tools/Urho3DPlayer/Urho3DPlayer.cpp