Honda Pilot tuning / lane centering fixes (#408)

Tuned kP and kI and Tire Stiffness Factor settings.
Fixes lane centering issues in the following situations:
1.  Hugging of left lane line during fast left curving roads
2.  Hugging of right lane line during fast right curving roads
3.  Left bias in fast lane on crowned roads (sloping down to the left)
4.  Right bias in slow lane on crowned roads (sloping down to the right)
Works better when lane_width = 2.85 (vs 3.7 default) in pathplanner.py

selfdrive/car/honda/interface.py

@@ -294,8 +294,8 @@ class CarInterface(object):
       ret.wheelbase = 2.81
       ret.centerToFront = ret.wheelbase * 0.41
       ret.steerRatio = 16.0         # as spec
-      tire_stiffness_factor = 0.444 # not optimized yet
-      ret.steerKpV, ret.steerKiV = [[0.38], [0.11]]
+      tire_stiffness_factor = 0.82 
+      ret.steerKpV, ret.steerKiV = [[0.5], [0.22]]
       ret.longitudinalKpBP = [0., 5., 35.]
       ret.longitudinalKpV = [1.2, 0.8, 0.5]
       ret.longitudinalKiBP = [0., 35.]