Ported to Arduino Due platform

This small patch enables the usage of the Library with the new Arduino ARM-based boards like the Due as noted in issue #37. Changes mainly reflect the change from the Harward-Architecture of the AVR microcontrollers to the Von-Neumann-Architecture of the ARM chips, which makes the separation between program- and data memories obsolete.

I did some testing and everything worked, but this should probably be tested more thoroughly by other people before being merged upstream.