Jia's Fork of DXU Firmware

This is my modification of the DXU's firmware from yyh1002's dual extruder design for Ultimaker 2+. Following are the changes so far:

• Integrated Tinkergnome 18.10
• Made configuration changes for DWMaker Extended
  • Change Z range to 305
  • Change max temperature to 290
  • Change max bed temperature to 135
  • Lower max acc to 1700.0 2000.0
  • Lower max jerk to 10.0
  • Lower bang-bang check interval to 4s
  • Limited Y axis to 222 for metal slider block.
  • Adjust all material diameter to 1.75.
• Ported the retraction after insert material from the original firmware.
• Port User Function from Marlin for preheat chamber etc...
• Add temperature hysteresis to the fan on/off logic.
• Introduce T flag for M301 command for choosing PID setting.
• Optimize tool change behavior.
• Print tinkergnome related settings
• Porting marlin PR#2432 for higher temperature
• Restore PID filter back to 0.95 for quicker response.
• Make M500 and M501 store/restore tinkergnome settings as well.