Fixed set Start and set Goal

Closes #13, Closes #14

in sdp_project_demo.py :
- grouped class variables in MainWindow
- grouped Qt Connections 
- removed a bunch of lines that didn't do anything
- properly connected startChanged Signal to setStartPose function
- properly connected goalChanged Signal to setGoalPose function
- rewrote set[Start|Goal]Pose functions to call getStartPose, getGoalPose
- removed hardcoded line from testing solve button

in ProblemWidget.py :
- renamed startPose2D and goalPose2D to startPose and goalPose
- rewrote setStartPose and setGoalPose to take x,y,yaw variables instead of unknown value
- rewrote getStartPose and getGoalPose, no need to catch 3D case

in pose2DBox.py :
- added missing import required for pi
- renamed rot to yaw, ase to match variable name elsewhere
- lowered range to match range limit of bounds
- rewrote setPose removing reference to ompl state
- rewrote getPose removing call to ob.State and ob.SE2StateSpace
- rewrote poseChange, Signal being emitted was [0,0,yaw,x,y,0]? now [x,y,yaw]