Import vanilla combat_tactics.txt from v1.11.1
Merge branch 'vanilla' into beta
Improve/Add combat tactics for Roman leaders.

Higer chance of forming a shield wall during skirmish, and of advancing during melee.
Additionally adding a new tactic for ending the skirmish and entering melee early.
Add bookmarks.txt files to the compatibility mods, with the Old Gods bookmark back at the top (and thus as the default).