Note that 'base' is essentially 'base_link' but rotated by 180
degrees over the Z-axis. This is necessary as the visual and
collision geometries appear to also have their origins rotated
180 degrees wrt the real robot.

'tool0' is similar to 'ee_link', but with its orientation such
that it coincides with an all-zeros TCP setting on the UR
controller. Users are expected to attach their own TCP frames
to this frame, instead of updating it (see also [1]).

[1] http://wiki.ros.org/Industrial/Tutorials/WorkingWithRosIndustrialRobotSupportPackages#Standardised_links_.2BAC8_frames

xacro arguments. Replaced all tabs with spaces. Updated the UR10 urdf files.

Also removing virtual joint from MoveIt! configuration.

base_link a dummy link to better support MoveIt.

Corrected UR10's urdf to faithfully represent joint effort thresholds, velocity limits, and dynamics parameters.