ON GEN7 there is no temperature reading when power is off.. so Marlin
would kill itself. There seems to be an update from "Traumflug" on GEN7
using standby VCC for thermistors.

- redo disable Beeper if PIN is set to -1

- Added support for ATMega1284

 arduino-0023/hardware/arduino/cores/arduino/wiring.h
this is necessary if the avr libraries are recent, but arduino is old. Alternative: newer arduino

advance and ultipanel not any more in default config

This reverts commit 651cde8b98.

Soft PWM. (Sanguinololu can also have PID temperature control)
Interrupt save WRITE for addresses > 0x0FF

- The temperature control is pretty much complete
  (not sure what to do w/ autotemp though)
  Changed the pins assignment to clearly separate bed and extruder heaters
  and temp sensors, changed a bit how termistor tables are handled.
- The steppers control is rudimentary
  (only chanages what pins it uses depending on the active_extruder var,
   but that's enough for switching extruder in the start.gcode in the
   the profiles)
- Tested only w/ RAMPS 1.4