calibration: turn countdown_ into parameter

For smooth slow motions through the zero crossing it can
be helpful to increase the distance before passing through it from low to high.

As a longer default time changes the well-established startup initialization
to the worse (more collisions) it's better to turn it into a parameter without
changing the default.

pr2_calibration_controllers/include/pr2_calibration_controllers/joint_calibration_controller.h

@@ -74,6 +74,7 @@ class JointCalibrationController : public pr2_controller_interface::Controller
   int state_;
   bool announced_calibration_success_;
   int countdown_;
+  int tics_moving_past_calibration_reading_;
 
   double search_velocity_;
   double original_position_;

pr2_calibration_controllers/src/joint_calibration_controller.cpp

@@ -90,6 +90,9 @@ bool JointCalibrationController::init(pr2_mechanism_model::RobotState *robot, ro
     return false;
   }
 
+  tics_moving_past_calibration_reading_ = 200;
+  node_.getParam("tics_moving_past_calibration_reading", tics_moving_past_calibration_reading_);
+
   bool force_calibration = false;
   node_.getParam("force_calibration", force_calibration);
 
@@ -227,7 +230,7 @@ void JointCalibrationController::update()
       }
     }
     else
-      countdown_ = 200;
+      countdown_ = tics_moving_past_calibration_reading_;
     break;
   case MOVING_TO_HIGH: {
     vc_.setCommand(search_velocity_);