The bug2_create from dennismelamed

Title: Contact Sensor Based Implementation of iRobot Create Navigation Around Obstacles to Goal Postions
Author: Dennis Melamed
Based off of the pathfinding algorithm know as "Bug 2."
A more complete explanation with visuals (by Howie Choset at Carnegie Mellon University) can be found here:
http://www.cs.cmu.edu/~motionplanning/lecture/Chap2-Bug-Alg_howie.pdf
Overall Process:
-Calculate shortest distance to target, record the angle from the target to a zero angle position (this describes the line to the target, aka the "m-line")
-Drive along the m-line until the target is reached or a collision is detected
-If a collision is detected, follow the edge of the object collided against clockwise until the m-line is regained
-Continue driving towards target following the m-line, repeat object circumnavigation as required until target reached.
More Detailed Flow:
-An angle to the goal position is found and rotated to
-The robot moves forward until a collision is detected or the goal position is reached
-if a collision is detected:

 -an angle respresenting the line from the current position to the goal position is stored

 -the robot drives back a short distance,

 -rotates 90 degrees counter-clockwise,

 -drives forward checking for a collision

 	- the above process repeats itself until a collision is not detected

 -if there is no collision after a certain distance:

 	- this indicates the robot has gone off an edge of the obstacle

 	-The robot drives forward an additional robot-length,

 	-begins testing again as though a collision had just been detected

 -Once the robot is at the same angle from the origin as the goal position is, the m-line has been regained

 -The robot rotates to face the goal position and begins driving toward it again

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