Update submodule documentation

Fixes #1762
submodule: check alloc and name presense
Merge pull request #1763 from nvloff/nameless_submodule_segfault

submodule: check alloc and name presence
More tests for ambiguous OIDs across packs

The test coverage for ambiguous OIDs was pretty thin.  This adds
a bunch of new objects both in packs, across packs, and loose that
match to 8 characters so that we can test various cases of
ambiguous lookups.
Merge pull request #1765 from arrbee/ambiguous-oids

More tests for ambiguous OIDs across packs