Firmware was forgetting the z_fade_height in Planner, set by M420 Z<f>,
after each reset or loading settings from EEPROM. Added the float
z_fade_height to EEPROM-Storage, now remembers the value.

DAC_STEPPER_DFLT wasn't changed to DAC_MOTOR_CURRENT_DEFAULT in all
places on PR #6124

# This is the 1st commit message:

MCP4728 consistency & fix ultralcd.cpp

The MCP4728 DAC controls the stepper motor current strenth on the
PRINTRBOARD Rev F and RIGIDBOARD V2 boards.

PR #5792 on 9 FEB 2017 implemented default drive percentages but only on
the RIGIDBOARD V2.

This change moves the default settings to Configuration_adv.h.

Also, ultralcd.cpp won't compile because of a type def conflict.
Changed it to match the one in stepper_dac.cpp

===========================================================

reword stepper curent section for clarity

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change name & improve comments

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changed name from A4JP to SCOOVO_X9H per PR #6139

# This is the commit message #2:

fix typo

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clarified BLTouch calculation & changed comment delimitters/flags

I found it hard to pickout the various sections in this area so I
changed most comments from // style to /** ... */

Made the BLTouch calculation simpler and clarified the units of measure
for the result.

============================================

add changes to example configurations

============================================

add TinyBoy2 to this PR & add BLTouch Delay

The offset for Z_DUAL_ENDSTOP (z_endstop_adj) is already in Marlin.
This PR just makes it a configuration item.

z_endstop_adj is initialized in two places so both had to be modified.

The TB2 is a Indiegogo funded 3d printer. It uses a MKS SMELZI V1.0
main board (based on MELZI, i.e. Sanguinololu). I comes as a complete kit,
including display and panel.
Two variants exists, L10 and L16, with a height of 100 and 160 mm.
The heating function of the provided bed can enabled by soldering a
thermistor and some wires to it.

Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>

The OLED is driven by an SSD1306, connected to the board via
I2C, the rotary encoder is connected to 3 GPIO pins.

Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>

Made the double touch portion a conditional compile based on the
PROBE_DOUBLE_TOUCH flag.

==============================================

Bugfix

The current G38 only stopped a move if it involved the Z axis.

Moved all the G38 code to it's own section and put it where it would
always be executed no matter what axis was moving or if the endstop was
enabled.

Also added a comment to configuration_adv to alert the user the double
tap had to be turned on.

==============================================

Change G38 back to using Z_MIN_PROBE

There's no Z_MIN endstop if Z_DUAL_ENDSTOPS is enabled and you have them
set to the top of the gantry.

G38 started out as using the Z_MIN_PROBE pin.  I don't remember why we
changed it to the Z_MIN endstop.