Handle wrapping of MCB encoder count (ros ticket #5010)

[ahendrix]

Encoder count is only 32bits. It ''may'' be possible for encoder position to wrap in long-term operation. The best way to avoid the wrapping issue, is to extend the encoder count to 64bit in ethercat_driver. However, care needs to be taken to correctly account for robot calibration offset.

trac data:

• Owner: wheeler
• Reporter: dking
• Reported at: Tue Feb 8 20:56:38 2011
• URL: https://code.ros.org/trac/wg-ros-pkg/ticket/5010