Tidied up delta auto-calibration code. We now use least squares for 3,
4, 6 or 7-factor calibration.
When doing delta calibration, if a probe offset was used to adjust the
head position when probing, use the actual head coordinates instead the
probed coordinates.
Bug fix: newline was missing at end of SD card file list sent to USB
when in Marlin emulation mode.
Bug fix: Heater average PWM report (M573) sometimes gave inaccurate
values when the S parameter was used.
Implemented rr_config web request for zpl's latest web interface
Implemented 7-factor auto calibration for delta printers
Fix bug with fileinfo calls corrupting memory
M563 can now be used to delete tools
Fixed bug with reading file info
Don't return status as Printing if just running a macro
Restored Json buffer back to 2000 bytes so as to return more files on SD
card
Limit the amount of moves we buffer so as to react faster to speed and
extrusion rate changes
Return print time left estimates in M105 S2 status response if printing
a file
Show stepper motor currents as integers and do some rounding to get more
accurate values
Added almost instant pause functonality
Support pause and resume macros
Support nested macros
Support zpl's web interface
Merge in zpl's web interface and network changes
Add R parameter to M105 command for PanelDue
M98 can now run macros from any SD card folder
Fixes some possible issues in delta printing code
Don't apply Z probe XY correction when probing at current point with G30
with a P parameter
Added experimental simulation code, controlled by M37 for now
Added X and Y z-probe offsets to G31 command
Reworked G31 and G32 to do less work in the step ISR and to support Z
probe on delta printers
Z probe modulation pin is now selected using M558 R parameter instead of
probe type
