Spell School Format

WARNING: currently custom spell schools are only partially supported:

it is possible to use custom spell schools in bonus system
it is possible to make skill for specializing in such spell
it is possible to specify border decorations for mastery level of such spell in spellbook

it is NOT possible to add "bookmark" filter for spellbook for spells of such school

	// Internal field for H3 schools. Do not use for mods
	"index" : "",
	
	// animation file with spell borders for spell mastery levels
	"schoolBorders" : "SplevA"