GainStruct can be used to set gains of groups
 
    The struct created by this function can be used to set a variety of
    gains and control parameters on a group of modules. A list of all 
    currently available gains is below:
 
                           time [s]
                controlStrategy [HebiEnum]
                  mStopStrategy [HebiEnum]
                     positionKp
                     positionKi
                     positionKd
                     positionFF
               positionDeadZone
                 positionIClamp
                  positionPunch
              positionMinTarget
              positionMaxTarget
              positionMinOutput
              positionMaxOutput
      positionTargetLowpassGain
      positionOutputLowpassGain
               positionDOnError
                     velocityKp
                     velocityKi
                     velocityKd
                     velocityFF
               velocityDeadZone
                 velocityIClamp
                  velocityPunch
              velocityMinTarget
              velocityMaxTarget
              velocityMinOutput
              velocityMaxOutput
      velocityTargetLowpassGain
      velocityOutputLowpassGain
               velocityDOnError
                       effortKp
                       effortKi
                       effortKd
                       effortFF
                 effortDeadZone
                   effortIClamp
                    effortPunch
                effortMinTarget
                effortMaxTarget
                effortMinOutput
                effortMaxOutput
        effortTargetLowpassGain
        effortOutputLowpassGain
                 effortDOnError
 
    The online documentation provides more information about the 
    individual gain settings and control parameters:
    http://docs.hebi.us/core_concepts.html#controller_gains
 
    GainStructs can be loaded and saved to an XML file format with 
    functions provided in HebiUtils.  This format is the preferred way
    of storing and loading gains for different demos / applications.  More
    information on the XML format can be found at:
    https://github.com/HebiRobotics/hebi-xml/blob/master/GAINS.md
 
    Empty entries in the struct and NaNs for any individual values in 
    gains or control parmaters are ignored. In these cases any existing 
    setting on the module for that parameter will remain unmodified.  
 
    Example (Loading gains from XML file and setting on a group)
        gains = HebiUtils.loadGains('myGains.xml');
        group.send('gains', gains);
 
    Example (Saving gains to XML file)
        gains = group.getGains();
        HebiUtils.saveGains(gains, 'myGains.xml');
 
    Example (Manually setting gains):
        gains = GainStruct()
        gains.controlStrategy = [4 4];
        group.send('gains', gains);