Object Group can be set property "active" to "false" to disable all
objects within at new game (except Spawn Areas, those are treated
individually).
(de)activateMapChangeArea script rewards become
(de)activateMapObjectGroup
Persistence of active object groups in saves is implemented.
Debug map showcases the new feature, with beer !
* Requirement class moved from model.conversation to model.script
* Added requirement questLatestProgress : quest stage must be reached, but no stage with superior ID must be reached.
* New key requirements conditions type (item/gold/bonemeals) consumption (more or less than value, never strict checking, either <= or >=).
