dynamic factions

Allow dynamically created factions, with dynamically updated reputations between each pair of factions. This will allow for different groups of hostiles to fight each other as well as the player, and for the player to gain or lose favor with various factions through quests, dialog etc.

The issue names no files, tests, or entry points. Begin by mapping how factions, hostile groups, quests, and dialog are currently represented, then determine the design needed for dynamically created factions and pairwise reputation. Done means factions can be created at runtime, reputations update between every pair, and those changes affect hostile groups and player interactions.

Written by the indexing model from the issue text.