Modularize SHACL profiles

[rjyounes]

Modularize SHACL profiles to promote conceptual clarity and re-use, both within bibliotek-o and the domain-specific ontology profiles. See demonstration and comments in PR #65.

[rjyounes]

See changes in PR #65 and accompanying comments

[VladimirAlexiev]

@rjyounes where are these shapes? I only find references to them (eg https://github.com/search?q=bibliotek-o_shapes&type=Code) but not the files

[zimeon]

@VladimirAlexiev work on SHACL was continued with the ARM ontology, see for example https://github.com/LD4P/arm/blob/master/activity/validation/shacl/arm_activity_property_shapes.ttl

[sfolsom]

@VladimirAlexiev see also our maintenance doc for more context: https://github.com/LD4P/arm/blob/master/doc/shacl_maintenance.md