New options for PPO

I added some new options to PPO. Besiges the "normal" histogram based signal generation, its now possible to use the "speed" (PPO - previous PPO) as signal generator.

Thresholds for crossing situations, non crossing situations and possible rebound situations can be configured. In this case, the "normal" signal generation is ignored.

So it's possible to adjust the personal trading strategy wit the PPO indicator.