Merging from agent_plugin (Nate).
sExpression interface (initial commit)
Style
Added imu and force sensors to nao.
Added center circle lines
Working in the integration.
Merge branch 'patrick' of https://github.com/osrf/robocup_3d_simulation into patrick

Conflicts:
	robocup_agent_plugin/include/robocup_agent_plugin/AgentPlugin.hh
Cleaning and updating readme.
Update the readme.
Fix landmark positions.
Including the game state in the AgentState message. Creating a function in the sExprInterface for spawning the agent.
Adding damping to the joints, velocity decay to the ball, and unpinned initial position.
Fixing the landmark goad post heights (0.8 instead of 0).
More updates
Add joint limits.
Using the official game state names.
Running server updates every ~20ms and perception updates every ~60ms.
Updating gyro and accelerometer every cycle and updating agent data every 20ms.
Synchronization between worldplugin and agents.
Rearranging joint names index array.