The code fails when trying to load robots with prismatic joints

[benjamin-levin]

I tried exporting a robot with a prismatic joint and it failed with an error message claiming that a Prismatic Joint needs to be initialized with limits. When I looked in the urdf.py file I realized that the limits were commented out. When I uncommented that code and added the limits I desired it fixed the problem. Please fix the code to get the real joint limits for both revolute joints and prismatic joints. Fortunately, the robot I am working on at the moment only has 1 prismatic joint but my band-aid fix will not work in other cases.