loadGains loads gains for group from disk (XML)
More information on the gains XML format can be found at:
https://github.com/HebiRobotics/hebi-xml/blob/master/GAINS.md
This method loads gains from a human readable file into a
GainStruct. Note that this includes only the control
strategy and the corresponding gains, and may exclude some
fields such as 'time' (set to now) or 'mStopStrategy'.
Example
% Create a test XML file with empty gains
gainFile = HebiUtils.saveGains(GainStruct(), 'MyGains');
% Load those gains back from the XML file
gains = HebiUtils.loadGains(gainFile);