Merge branch 'Marlin_v1', remote-tracking branch 'origin/Marlin_v1' into Marlin_v1
Add option to only check endstop when homing
Update endstops only for homing. (use less resources when not used)
added M503 to display eeprom storage, and renamed eeprom routings. This version is compatible with the qtmarlin eeprom-tab.
Merge branch 'Marlin_v1' of https://github.com/ErikZalm/Marlin into Marlin_v1
Working version of multiple extruders (up to 3)
- 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
Merge branch 'Marlin_v1', remote-tracking branch 'origin/Marlin_v1' into Marlin_v1
Merge branch 'Marlin_v1' of https://github.com/dob71/Marlin into Marlin_v1
repaired homing position setting.
moved <stdio.h> to more dominant location.
z homing sound fix, for now until the actual cause is found..
Fix M201 not saving settings in all places, so the changes did not get written into EEPROM
fixed the st_synchronize. it would have continued if there is only the last move of the buffer being stepped.
added autostart procedure trigger to the ultralcd menu
added a partial release option to "m84" aka "stepper release". If you do tiny layers, you might want to keep the z-axis powered to not loose height positioning after homeing.
extruder runout prevention.
made runout prevention independent of tempeorarily set esteps
better values.
prevent too long extrudes, or too cold extrudes
disable steppers in runout prevention