Updated configs for Ars Magica 1.2

This is the biggest change deferred to 2.9 releases, as it breaks all existing Ars Magica power systems due to the new model for spellcasting in this update.
2-DEV-157 update

Will not be used for a stable release.
Will be used to cut experimental releases as 2.9.2.0.
2.9.2.0-EXP-MAIN update

Includes all the 2.8.7.5 changes.