add yapf style and apply yapf to format all Python files

This recreates pull request #2192

examples/pybullet/examples/changeDynamicsMass.py

@@ -2,14 +2,14 @@ import pybullet as p
 import time
 
 p.connect(p.GUI)
-cube2 = p.loadURDF("cube.urdf",[0,0,3], useFixedBase=True)
+cube2 = p.loadURDF("cube.urdf", [0, 0, 3], useFixedBase=True)
 cube = p.loadURDF("cube.urdf", useFixedBase=True)
-p.setGravity(0,0,-10)
-timeStep = 1./240.
+p.setGravity(0, 0, -10)
+timeStep = 1. / 240.
 p.setTimeStep(timeStep)
-p.changeDynamics(cube2,-1,mass=1)
+p.changeDynamics(cube2, -1, mass=1)
 #now cube2 will have a floating base and move
 
 while (p.isConnected()):
-	p.stepSimulation()
-	time.sleep(timeStep)
+  p.stepSimulation()
+  time.sleep(timeStep)