Multicast has known issues (see #12999 and #12993). This change moves
multicast into a plugin, and deprecates it in the docs. It also allows
for plugging in multiple zen ping implementations.
closes#13019
allow to configure on the index level which blocks can optionally be applied using tribe.blocks.indices prefix settings.
allow to control what will be done when a conflict is detected on index names coming from several clusters using the tribe.on_conflict setting. Defaults remains "any", but now support also "drop" and "prefer_[tribeName]".
closes#5501
Yannick Welsch
Ryan Ernst
Clinton Gormley
David Pilato
Simon Willnauer
Shay Banon