- fix broken `M421` due to less-than-careful optimization
- add HOME_AFTER_DEACTIVATE define to advanced config so not everyone has to rehome after steppers are deactivated
- misc. cleanups (remove unused label, unused variables)

 - Add crc16 utility function
 - Implement CRC16 for config store, remove old checksum, increment layout version
 - Move UBL mesh store/load to MarlinSettings; increment UBL_VERSION
 - Begin to lay out MAT structure, prototype functions, etc.
 - Rename ubl.state.eeprom_storage_slot to .storage_slot
 - Misc. optimization
 - Cleanup/standardize/improve some messages

This is a work in progress!

* M421 Mesh Point Offset and misc. UBL clean up

Allow M421 to accept an offset as well as absolute value for a specified
mesh point.
And misc. UBL clean up to reduce redundent code.

* Better error checking for M421

* Fix M421 Y index bug

I just noticed....  We've had a Y index bug for who knows how long?

- update comment section
- redefined P5 grid
- minor clean to probe radius routine
- updated EEPROM version to V37 according remark in #6517

add BLTouch-related messages in english and (rusty) french;
add missing endstops.h in ultralcd.cpp;
fix misc. compiler warnings;
fix lsf_reset - ZERO macro can't handle a pointer as it would only memset the size of the pointer, not the size of the entire struct

This is what I did yesterday:

- basicly gave the tests more comprehensive names; put all the
declarations at the top; got rid of the magic negative C-value (renamed
to P + A, O, T)

- "cos(RADIANS(180 + 30 * axis)) * (1 + circles * 0.1 * ((zig_zag) ? 1 :
-1)) * delta_calibration_radius" compiles wrong is zig_zag statement is
without brackets

- DELTA_TOWER_ANGLE_TRIM reset to 3 values (the calcs use the 3th value
to normalize will not compile otherwise)

-Wrote 3 dummies to keep EEPROM lenght the same

-Reset the configs to the 'original' with autocal + menu disabled (but
can be enabled of course)

More consistent with M665 where C-value is allowed as well, then
normalized

* relocated ubl state to config. store:
 * removed a number of ubl state variables and padding which were largely unused - saved 58 bytes of both SRAM and EEPROM;
 * modified ubl sanity_check - no longer checks removed state variables that were otherwise unused, where checking didn't seem to accomplish anything, ultimately;
 * removed pre_initialized state, saving 64 bytes of SRAM;
 * removed automatic saving of UBL state after UBL activation/deactivation;
* consolidated multiple GRID_MAX_POINTS_X/Y to 'Global Leveling' section of EEPROM;
* minor update to G29 Sx notes/instructions;
* renamed mesh load and save parameter to 'slot' from 'm' for clarity;

Adding '7-point' tower angle correction calibration

- Making M665 compatible with repetier (see
http://reprap.org/wiki/G_code#M665:_Set_delta_configuration)

- M665 B also sets the radius for manual calibration menu

- Converting tower ajustment definitions to arrays - tower angle
corrections compatible with Esher 3D wizzard

- Only tower angles need to be adjustable with M665 and stored to EEPROM
- tower radius and diag rod can be adjusted in the FW only with #define

This data corruption problem is very difficult.  Just changing the code
a little bit changes whether the problem even happens and what is
affected.  I need these changes in the main branch so I can operate with
the extra debug code always available and turned on.

Everything is setup such that if M100 is turned off or DEBUG(ECHO) is
turned off, the code is not affected.   M100 has been made a little bit
more inteligent so it can display the serial command buffers in a more
meaningful way (because the data corruption seems to often times end up
in that area).

Configuration_store.cpp - changed a couple of print statements so the
values were printed.  The old method resulted in the formula being
printed.

ubl_G29
1) added support for R option to P4.  Now probes all points unless R is
present and the number is greater than 0.

2) P2 - moved map print statement so it showed the point that was
currently being probed,  The old location did this only for the first
point.

3) P4 - Moved the map print for the same reason.

ultralcd.cpp - changed "Mesh Editor :" to "Mesh Editor" because the LCD
draw routine puts a ":" in automatically so you end up with an extra ":"
using the old message.

- On `DELTA` the `M665 H` option supplants `M206`
- On `DELTA` `NO_WORKSPACE_OFFSETS` only reverts `G92` behavior
- Spawn 4 conditionals based on `NO_WORKSPACE_OFFSETS`
- Optimize coordinate space conversion for `DELTA` workspace
- To keep EEPROM version, retain `home_offset[XYZ]`, just ignore XY

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.