Add Chrysler ACC cancel button (#127)

* initial signals for chrysler pacifica 2017 hybrid

* add gear status PRNDL

* tighten up speed bits. brake pressue max comment.

* value table for gear status

* speed of right vs left side of car

* units for speed_right

* Set packet lengths, adding steering rate, adjusted speed

* Speed, braking, and distance signals

* turn signals

* Revert "turn signals"

This reverts commit 91f6507031a989f8e15ee8fcf67c3a730ee1909f.

* turn signals

This time without accidentally overwriting energee's signals.

* turn signal lights (and thus hazard lights)

* high beams for genericToggle

* high beams also. likely dashboard message.

* acceleration pedal for gasPressed

* seatbelt unbuckle message

* LKAS lane-keeping assist dashboard indicators

* auto park disable button

* auto park turning on button

* auto park signal unknown

* autopark has control

* another signal for autopark having control

* autopark parallel and perpendicular mode. maybe turning wheel.

* another auto park perpendicular bit

* another bit for if autopark or human has control

* another steering angle signal, this is more noisy and lags the other
one.

* blind spot warning signal
why isn't the left warning near the right warning?

* parksense disabled signal

* lkas steering torque maaaaybe

* correct size and signed for lkas maaaybe steering torque

* lkas incrementer and checksum

* lkas checksum
thanks to work by Charlie Miller and Chris Valasek!

* gear checksum, message lengths, better names

* more message lengths and checksum

* more lengths

* the rest of the normal message lengths

* lots more signals

* blind spot left alert

* autopark checksum

* one more bit for energy curve

* more braking

* fix speed factor

* radar messages for pacifica from private fusion canbus

* change to standard COUNTER and CHECKSUM

* another speed signal

* dashboard signals, perhaps acc

* ACC steering wheel buttons

* unknown signals

* more unknown signals

* new type of message on private fusion

* private fusion unknown messages

* autopark turning status

* more auto park

* fix wheel speed signal size

* radar distance signal fix

* radar LAT_DIST, LONG_DIST and guesses for REL_ACCEL and REL_SPEED

* speeds that correspond with long dist messages

* units for the d_* REL_SPEED

* acc speed config units

* ACC accel and decel

* ACC braking messages

* guesses for ACC

* more acc

* random signals

* fix lkas signal, gas vs electric signals

* steering angle units

* switch PRNDL to big endian because I suspect cabana and OP CanParser do
not work the same way for little endian.

* switch the signals OP uses to big endian to work around little endian
limitation

* wheel speed factors and fix side speeds

* ACC cancel button

chrysler_pacifica_2017_hybrid.dbc

@@ -206,6 +206,7 @@ BO_ 571 WHEEL_BUTTONS: 3 XXX
  SG_ ACC_SPEED_INC : 2|1@0+ (1,0) [0|255] "" XXX
  SG_ ACC_SPEED_DEC : 3|1@1+ (1,0) [0|3] "" XXX
  SG_ ACC_FOLLOW_INC : 8|1@1+ (1,0) [0|15] "" XXX
+ SG_ ACC_CANCEL : 0|1@0+ (1,0) [0|15] "" XXX
  SG_ COUNTER : 15|4@0+ (1,0) [0|15] "" XXX
 
 BO_ 669 NEW_MSG_29d: 3 XXX
@@ -402,6 +403,7 @@ CM_ SG_ 729 LKAS_STATUS_OK "Set to 0x0820 when LKAS system is plugged in.";
 CM_ SG_ 288 UNKNOWN_CHECKSUM_120 "not the LKAS checksum";
 CM_ SG_ 288 GAS_ENGINE_RPM_MAYBE "lags acceleration, perhaps gas engine";
 CM_ SG_ 257 ENERGY_OR_RPM "perhaps energy consumption or RPMs";
+CM_ SG_ 571 CHECKSUM_23B "standard checksum";
 CM_ SG_ 270 ELECTRIC_MOTOR "0x7fff indicates electric motor not in use";
 CM_ SG_ 291 ENERGY_GAIN_LOSS "unsure what this actually is";
 CM_ SG_ 291 ENERGY_SMOOTHER_CURVE "unusre what it is, but smoother";