restructure of graph structures to facilitate logic

[lzehl]

solving #3
Restructuring everything in graphStructures folder into:

brainAtlases/
    »BA«.jsonld (naming convention: BA atID basename)
brainAtlasVersions/
    »BA«/ (naming convention: BA atID basename)
        »BAV«.jsonld (naming convention: BAV atID basename)
parcellationEntities/
    »BA«/ (naming convention: BA atID basename)
        »PE«.jsonld (naming convention: PE atID basename)
parcellationEntityVersions/
    »BAV«/ (naming convention: BAV atID basename)
        »PEV«.jsonld (naming convention: PEV atID basename)
commonCoordinateSpaces/
    »CCS«.jsonld (naming convention: CCS atID basename)
commonCoordinateSpaceVersions/
    »CCS«/ (naming convention: CCS atID basename)
        »CCSV«.jsonld (naming convention: CCSV atID basename)