Currently the (cavalry) stable template is a child of the barracks template, which is odd; the elephant stable, dog kennel, and workshop all inherit from the military template, not from the barracks template.
- moves template_structure_military_barracks_stables.xml to template_structure_military_stable.xml
- updates all its children accordingly
- merges values from pers_stable.xml into the new generic template
- changes generic name Stable (singular, without s)
- standardizes rubble sizes to 5x5 (pers had 4x4)
- corrects specific name for Greek factions
- adds foundation actor to kush_stable.xml