AC_WPNav: Fix some typos

Fixed some typos found in the code.

libraries/AC_WPNav/AC_Circle.cpp

@@ -174,7 +174,7 @@ bool AC_Circle::update(float climb_rate_cms)
         _angular_vel = MAX(_angular_vel, _angular_vel_max);
     }
 
-    // update the target angle and total angle traveled
+    // update the target angle and total angle travelled
     float angle_change = _angular_vel * dt;
     _angle += angle_change;
     _angle = wrap_PI(_angle);

libraries/AC_WPNav/AC_Circle.h

@@ -153,7 +153,7 @@ private:
     float       _rate;          // rotation speed of circle in deg/sec. +ve for cw turn
     float       _yaw;           // yaw heading (normally towards circle center)
     float       _angle;         // current angular position around circle in radians (0=directly north of the center of the circle)
-    float       _angle_total;   // total angle traveled in radians
+    float       _angle_total;   // total angle travelled in radians
     float       _angular_vel;   // angular velocity in radians/sec
     float       _angular_vel_max;   // maximum velocity in radians/sec
     float       _angular_accel; // angular acceleration in radians/sec/sec

libraries/AC_WPNav/AC_WPNav.cpp

@@ -482,7 +482,7 @@ bool AC_WPNav::advance_wp_target_along_track(float dt)
     }
 
     // Use vel_scaler_dt to slow down the trajectory time
-    // vel_scaler_dt scales the velocity and acceleration to be kinematically constent
+    // vel_scaler_dt scales the velocity and acceleration to be kinematically consistent
     float vel_scaler_dt = 1.0;
     if (is_positive(_wp_desired_speed_xy_cms)) {
         update_vel_accel(_offset_vel, _offset_accel, dt, 0.0, 0.0);