Two ideas for Rengar

With the aim of reducing his 100->0 burst-from-stealth potential.

1. Using his ultimate consumes all his current Fury and extends the stealth duration or the Fury-gaining duration after the stealth per point.

2. Empowered abilities have a seperate cooldown for their empowered states.

Both ideas aim at the idea to block access to the triple Q from stealth, which is where Rengar's main burst comes from. If it is necessary, he could potentially be buffed on other levels if these changes nerf him too much.