SHACL - Batched revalidation

[hmottestad]

Currently the revalidation aspect of the ShaclSail loads all targets for a shape into memory, sorts them, then supplies them to the validation engine. The validation engine only operates on sorted data. A solution to this could be to load only the first 100 000 targets, sort and validate those, then load the next 100 000 and repeat. This wouldn't necessarily make things faster, but it would reduce memory usage and parallel validation might then be possible.