* Find matching hardware_interface using the required type
The name of the controller was used in order to find and start
the matching hardware interface.
In consequence this meant that one could only define one controller
for each hardware interface.
Now, the controller's required type of hardware interface is used
to find and start the matching hardware interface.
* separate read & update in controller
consume is defined as read+update, but update
does not include read in ros_control terminology.
* Handle latency in pipeline loop
The controllers need to update at a rate of *at least* 125Hz,
but the wait_dequeue_timed call could in theory slow the loop down to 62.5Hz.
The old ur_modern_driver worked around this problem by sending goals
at 4*125Hz.
This patch exploits the onTimeout method of a consumer to update with
the specified frequency of the control loop, even if no new state message
arrived after the previous command.
* publish wrench w.r.t. tcp frame
The messages had an empty frame_id before and could not be displayed in RViz
* support ros_control in indigo
Maintains default behavior of indigo that no controller activation is required.
Enabling required activation can be done by passing 'require_activation' as Always/OnStartup
to the ur_common.launch or by modifying corresponding launch files.
