Add driver enable pin support
Integrated PR from ameisso:
Added support for an enable io pin. This allows the external driver module to be shut off if needed (and if it has an enable pin or some external components attached to enable it) via the Library.
Note: this function is only to control the pin via the library, it does not automate the enable/disable functionality for you.
E.g. if you set it manually to "disabled" state, you need to manually enable it again before you try to send steps to the driver.
Note: this version contains a partially a "breaking" change if you use the brake-function of the library. The brake function has been renamed (typo corrected) thus if you use it, you simply need to change your code to use "isBrakeActive" instead of "isBakeActive" (old function mane with typo, library unfortunately cannot "bake" anything for you :-) )