Fixed|Hexen: Crash when starting a new game from end game finale

FI_StackClear() can have the side effect of setting a new game action;
in this case GA_ENDDEBRIEFING. However, when starting a new game
session we must ignore any actions from the InFine stop hooks.

Todo: Is FI_StackClear() meant to trigger stop hooks?

Also changed the order of the game action enums in x_event.h to
match the other games, however this has no impact on the execution.

IssueID #1750