Added BeBoPr++ configurations and PEPPER stepper board HAL component

These changes create BeBoPr++ configurations for the plain 4-axis (Pololu) configuration a the 5-axis Pepper driver based configuration. A pepper HAL component is added for (software) configuration of the stepper drivers on the PEPPER board. The configuration tree in this patch should be the base for future changes and extensions for BeBoPr++ based systems.

There's some code duplication. I've tried to reduce this by refencing files in parent directories as much as possible.

-- Bas