- Add support for 4th extruder
- Fix parentheses matching
- Apply coding standards
- Address issue mentioned at #1575

- Add BIT and TEST macros
- Add _APPLY_ macros to stepper.cpp to help with consolidation
- Consolidate code in stepper.cpp using macros
- Apply standards in stepper.cpp
- Use >= 0 instead of > -1 as a better semantic
- Replace DUAL_Y_CARRIAGE with Y_DUAL_STEPPER_DRIVERS

Added option to set Travel Acceleration (non printing moves).
The M204 options was a non sense (S for printing moves and T for retract
moves).

It has been changed to:
P = Printing moves
R = Retract only (no X, Y, Z) moves
T = Travel (non
printing) moves

I will add this info o G-Code wiki in reprap.org. I also advise to put
this info in Marlin next version changelog.

I forgot to enclousure the variable with #ifdef

because strtod() will read the E address value as if it was a base 10
exponent.

With this change a mechanical or optical switch may be used to check the
availability of the filament and when the filament runs out an M600
(filament change) command is issued. This is only done while printing
with an SD card.

This feature was requested several times (issue #679), but the requests
were not accepted since it was believed that this situation should be
handled at host side. However during an SD print the control is totally
on firmware and I think that during an SD print it should be handled by
the firmware.

The original code was posted at reprap forum
(http://forums.reprap.org/read.php?1,297350) by Lazymonk. I have only
corrected some bugs of the code and improved it by adding definitions to
the configuration.h in order to make it more standardized.

- Nonlinear auto bed leveling code (includes G29, G30, Z_RAISE_AFTER_PROBING). Cleaned it up to be a delta-specific AUTO_BED_LEVELING_GRID code path.
- Allen key z-probe deployment and retraction code. Cleaned it up and added safety checks.

- Moved sanity-checks to Marlin_main.cpp
- Applied to other configuration files
- Fixed formatting of ABL output
- Passing verbose level to probe_pt
- Miscellaneous cleanup
- Put CONFIG_STEPPERS_TOSHIBA into Configuration.h

- A redo of #1576, which missed topo_flag
- Always set verbose_level

add ```^ !(n_ENABLE_ON)``` for each stepper

  * "G1 X1 ; test" was not executing "G1 X1" due to never leaving comment mode.
  * "M117 Hello \;)" printed "Hello \" to the display due to not replacing serial_char properly.

Tested with the following commands:
    * M117 Hello ; test => displays "Hello" on display, ignores "test"
    * G1 X1 ; foo => moves 1mm in X, ignores "foo"
    * ; test => completely ignored, not even acknowledged
    * M117 Hello \;) => displays "Hello ;)" on display
    * M117 Hello \\;) => displays "Hello \" on display, ignores ")"

Autoretract was broken, looks like it was overlooked when the retracted flag was updated for multi extruders.

- Setting boundaries based on configured limits, contrasting with G28
(which forgets these limits?)

- Adapted “Enhanced G29” code referred to in #1499 and posted at
[3dprintboard.com](http://3dprintboard.com/showthread.php?3105-Auto_Bed_
Leveling-Enhanced-G29-command)
- Compatible with current G29 while adding some new arguments
  - `V` sets the verbose level for serial out
  - `T` (or `V` > 2) send a Topology report to serial out
  - `E` works the same way as before
  - `P` works as before (source used `n` or `U`/`u`)
  - `L`, `R`, `B`, `F` work as before
- Still needs sanity checking for `LRBF`

The `float` keyword should not be on these vars because they conceal
the outer vars, preventing them from obtaining known values before
being passed in `set_bed_level_equation_3pts`. Possibly related to
`Z_RAISE_BETWEEN_PROBING` not functioning.

When probing PCB´s I had the problem that i needed auto-leveling for specific areas (it´s never the same size).
Not much code, but very useful.
Now I use simply G29 L5 R55 F5 B35 P3 to probe a 4x6cm PCB before milling.
I used int for values... might be wrong...
I hope this time I got the right development tree. (tried first with https://github.com/MarlinFirmware/Marlin/pull/1130/commits)

I've insert the define and pointer entries for the Viki 2 and miniViki
from Panucatt in all of the example configs and main config. With these
additions and with pins done in the old single pin.h style...I was able
to get the display working fine save for needing to turn Delta Segments
per Second down. But that's a common graphics lcd issue being looked
into right now.

I need assistance in understanding how the new divided pins files fit
together because my previous attempts at trying to get it to work
appropriately didn't seem successful. This originally came from trying
to find out how to swap the XYZ Min and Max Endstop pins in the Azteeg
X3 Pro. It only comes with one set of connectors and they're Min
Endstops. My previous experience didn't turn out well trying to tell the
firmware to home to the Min Endstops so the best solution I found was to
swap the pins in the firmware. If I'm missing a conflict with a setup
other than delta please let me know, but it makes sense in my setup.

- Patch from #1453 for delta movement plan
- Fix: Set X with code X instead of adding to X

Only a missing ","... now it will compile again

- Also partial cleanup of Marlin_main.cpp with a smidgen of Doxygen.

Update ConfigurationStore to always write dummy values for disabled
options, including FWRETRACT, DELTA, and SCARA. Update the EEPROM
version to “V15.” Also fixes a buffer overrun with axis_scaling in
Config_ResetDefault.