Update simulation and physics for 2020

* Adjust drivetrain physics to match wpilib.drive expectations
* Use wpilib geometry and kinematics objects instead of raw floats

pyfrc/mains/cli_sim.py

@@ -0,0 +1,37 @@
+from os.path import abspath, dirname, join
+
+import halsim_gui
+import inspect
+import logging
+
+logger = logging.getLogger("pyfrc.sim")
+
+
+class PyFrcSim:
+    """
+        Runs the robot using WPILib's GUI HAL Simulator
+    """
+
+    def __init__(self, parser):
+        pass
+
+    def run(self, options, robot_class, **static_options):
+        halsim_gui.loadExtension()
+
+        # initialize physics, attach to the user robot class
+        from ..physics.core import PhysicsInterface, PhysicsInitException
+
+        robot_file = abspath(inspect.getfile(robot_class))
+        robot_path = dirname(robot_file)
+
+        try:
+            physics = PhysicsInterface._create(robot_path)
+            if physics:
+                robot_class._simulationInit = physics._simulationInit
+                robot_class._simulationPeriodic = physics._simulationPeriodic
+
+            # run the robot
+            return robot_class.main(robot_class)
+
+        except PhysicsInitException:
+            return False