Change IVORN prefix to LVC
Change the IVORN prefix from
ivo://gwnet/LVC, because GCN traditionally uses the text after the
/ to indicate the name of the mission, which most closely corresponds to "LVC", short for "LIGO/Virgo Collaboration".
The IVORN path used to be
LVC, but changed to
gcn_sender when Scott Barthelmey made the change to pass through our VOEvents without any modification.
Copied from emfollow/userguide!20 (merged)