Extending measured joint state

[pkazanzides]

The current joint state includes position, velocity and effort (as well as joint name). It would be useful to include information currently available in prmActuatorState, including:

• Home switch status
• Forward/reverse limit switch status (hardware limits)
• Forward/reverse software limit status (software limits)
• Joint homed
• Joint in motion
• Joint powered on

In my opinion, the first two items above are most important, but the rest of the items are useful. For some robots, the "homed", "in motion" and "powered on" will be identical to the values returned by operating_state, but for other robots, they could be different.

I see two options to add this:

1. Create a new data type, called something like prmStateJointExtended, that has all the fields from prmStateJoint, plus these extra fields. The command name could be something like measured_jx, measured_js+ or measured_js_ext.
2. Create a new data type, called something like prmStateJointExtra, that has only these new fields. In this case, we would also need a new command called something like measured_jx.

My preference is for the first option, especially since it would provide better synchronization of data.