reorganise code, read plan in main (#11)

src/main.py

+import gcode2contour as gc
+import numpy as np
+import pickle
+from utils import load_plan
+
+
+if __name__ == '__main__':
+    plan = load_plan('plans/1.plan')

src/utils/__init__.py

 from .planning_tools import JTrajectory
+from .plan import load_plan

src/plan.py → src/utils/plan.py

 import gcode2contour as gc
 import numpy as np
 import pickle
-from utils import JTrajectory
+from . import JTrajectory
 
 
 def _emptyTraj(joints, arm):
@@ -78,7 +78,3 @@ def load_plan(filename):
     plan.trajs = trajs
     plan.cumul_time = ctime
     return plan
-
-
-if __name__ == '__main__':
-    plan = load_plan('plans/1.plan')