Add equivalent of pre-0.7.5 savedVariablesPerPlayer

[mezzodrinker]

In order to not push the load of having to manage the saved variables on the script authors, we should implement another variable storage which is an equivalent to the pre-0.7.5 savedVariablesPerPlayer storage. Effectively, the variables should be stored only for the combination of a player and a mob.

[mezzodrinker]

Further improvements

Added new saved variables settings "SavedVariablesPerEntity" and "SavedVariablesPerPlayerAndEntity" (resolves #95) SavedVariablesPerPlayerAndEntity is equivalent to SavedVariablesPerPlayer from earlier MobTalker2 versions; SavedVariablesPerEntity is equivalent to SavedVariables Legacy saved variables settings will (hopefully) continue to function like they used to Deprecated SavedVariables setting, will produce warning in log if still present Cleaned up and de-duplicated code

→ <<cset aa35d7c1c17d>>