Fix invalid indexes in loops.

Signed-off-by: Alexander Danilov <alexander.a.danilov@gmail.com>
Add macro DIRECTION_DDR and DIRECTION_POR to be able to move dir and step pins to different ports.

Signed-off-by: Alexander Danilov <alexander.a.danilov@gmail.com>
Add 5th and 6th axes. This will work with Sanguino (atmega644p) only, because it has additional PORTA.
Now DIR and STEP pins split between different ports (see config.h for detals).


Signed-off-by: Alexander Danilov <alexander.a.danilov@gmail.com>