Added CHDK support

Added so M240 can be used to trigger CHDK instead of sending an IR signal, see more about CHDK here http://captain-slow.dk/2014/03/09/3d-printing-timelapses/
Added CHDK support

Added CHDK support to take pictures instead of doing an IR command, see more about how to use it here http://captain-slow.dk/2014/03/09/3d-printing-timelapses/
Add support for disabling encoder control for feedrate multiplier

Signed-off-by: Matthew Schick <matthew.schick@gmail.com>
FWRETRACT in mm/s

Firmware retraction now stores the retract and recover speeds in mm/s
instead of mm/min. This makes it match the units of the maximum
feedrate, and fixes problems with modifying the value via LCD control
panel. From gcode, the values are still taken in mm/min to match the
units of G1 and similar, and they are converted to mm/s before they are
stored.

I also lowered the default retract feedrate to make it less likely to
cause problems for geared extruders when the user hasn’t bothered to
set a reasonable maximum feedrate, though users should be setting both
of these values to suit their hardware.
Merge pull request #829 from blddk/Marlin_v1

Added CHDK support
Merge pull request #833 from mattsch/optional_feedrate_multiplier

Add support for disabling encoder control for feedrate multiplier
Merge pull request #1 from ErikZalm/Marlin_v1

Update on 140315
Individual extruder flow rate

Extension of M221, Tune menu
Merge pull request #841 from Dim3nsioneer/Marlin_v1

Set flow rate (extrude-mutliplier) for each extruder individually
Extended Preheat options

Preheat LCD menus base on code by D-Base
Corrections for preheat extension in language.h
semantic changes in language.h
Bugfixes for language option 6 (russian)
Merge pull request #846 from Dim3nsioneer/Marlin_v1

Extended Preheat options
thermistortables.h: Add comments that table 60 uses beta=3950.
fix bug in M200 with multiple extruders
fix bug in M200 with multiple extruders
fix bug for dual extruders not working

some guy find that marlin not working good for dual extruders delta .
when type T0 or T1 to active extruder and  E0 or E1  move causing XYZ
motion . so i locales the bugs and fix it , I have dry run the fix.
Merge pull request #864 from whosawhatsis/M200

fix bug in M200 with multiple extruders
Merge pull request #866 from sakunamary/Marlin_v1

fix bug for dual extruders not working