Add baxter robot

 Define q0 as neutral if the robot doesn't have a SRDF

Unit test for all UR robots

Fix Anymal-Kinova SRDF collision matrix

Sync submodule CMake

Removing duplication of q0 in RobotLoader, instead using the one introduced in RobotWrapper

Add simple_humanoid

[talos_reduced] Fix inertia and mass to zero for optical links.

ref #67

In case we actually have a 1.0kg body, we can still put its name into
the one_kg_bodies arg.

Letting this unfix is adding 1kg for each link in pybullet.

Define unknown materials to hide URDF parser warnings

Fix Anymal SRDFs

Added conda info in README