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.
Improved speed of integer square root function
Fixed bug in GCodeBuffer IsEmpty function (thanks zpl)
Changed tool numbers to start at T0 in all /sys files
Added sample macro files
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
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
