2017-09-06 Philip Ilten <philten@cern.ch>
    Created warning when invalid seed returned in Extras
    Added check for invalid seed of jet in Extras
2017-09-04 Philip Ilten <philten@cern.ch>
    Removed mutable keyword for seeds in Extras
2017-08-29 Philip Ilten <philten@cern.ch>
    Trivial code formatting
2017-08-28 Jesse Thaler <jthaler@jthaler.net>
    Adding in more comments and documentation
    Changing choice of seeds in example to ensure larger number of constituents
    Edited description() to give number of seeds
    Made explicit how to use extras with dynamic_cast
    Tweaked doxygen documentation, making it version 1.0.0
2017-08-25 Philip Ilten <philten@cern.ch>
    Updates to documentation and minor cleanup
2017-07-25 Philip Ilten <philten@cern.ch>
    Initial creation
