Fix for missing event gating Crusade "showdown" timer

Honestly at a loss as to what happened to it, as I did implement
it. Here it is again anyhow.
Reflect changes to major_revolt CBs in vanilla 2.1.5/2.1.6
Changelog and version.txt update
Merge pull request #188 from zijistark/alpha

PB hotfix for Crusades and patch 2.1.6 compatibility