Change default rayCount/rangeCount parameters in URDF, allow parameterization (ros ticket #5025)

[ahendrix]

The hokuyo sensors in the PR2 gazebo setup use 640 rays for both the base and tilt lasers. This value is too high for the default PR2 settings, and it slows down the laser data generation.

These values should be lowered by default to between 180 and 350, and parameterized in their xacro macros. Ticket #5024 is to allow dynamic reconfiguration of these parameters.

trac data:

• Owner: natepak
• Reporter: watts
• Reported at: Wed Feb 16 14:31:32 2011
• URL: https://code.ros.org/trac/wg-ros-pkg/ticket/5025