loadHRDF loads an hrdf file and parses HebiKinematics objects
 
    This method is similar to HebiKinematics(hrdfFile) with
    additional support for tree structures and multiple end
    effectors.
 
    More information and background on kinematics:
    http://docs.hebi.us/core_concepts.html#kinematics
 
    More information on the HEBI Robot Description Format (HRDF):
    http://docs.hebi.us/tools.html#robot-description-format
 
    Example
       % Load an hrdf with a single end effector
       kin = HebiUtils.loadHRDF(hrdfFile);
 
       % Get the index mask corresponding to the used joints
       [kin, mask] = HebiUtils.loadHRDF(hrdfFile);
       position = fbk.position(mask);
       FK = kin.getForwardKinematicsEndEffector(position);
 
       % Get multiple end effectors and their corresponding masks
       [~,~,kins,masks] = HebiUtils.loadHRDF(hrdfFile);
       FK = cell(length(kins),1);
       for i = 1:length(kins)
         position = fbk.position(masks{i});
         FK{i} = kins{i}.getForwardKinematicsEndEffector(position);
       end