Feature pithoschanges

Includes the necessary changes for better integration with Pithos

Noticeable changes:

* Add signature for v2 maps
* Add v0 map hint
* Support map creation from a given object list
* Remove "archip_" prefix from maps and blocks created by archipelago
* Add rename functionality
* Immediately delete writeable objects when removing a map
* Add readonly option when mapping a volume
Overall

v0_size = pr->req->contaddr_size;  
if (map->version == MAP_V0 && v0_size != UNUSED) {
                        nr_objs =__calc_map_obj(v0_size, MAPPER_DEFAULT_BLOCKSIZE);
			if (map->nr_objs != nr_objs) {
				XSEGLOG2(&lc, E, "Size of v0 map invalid. "
						"Read %llu objs vs %llu expected",
					map->nr_objs, nr_objs);
				goto out_err;
			} else {
				map->size = v0_size;
			}
}

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