An early refactor. Some ideas became clearer as
development continued. Now the various phases are much
clearer and more easily reusable.
Also added a ton of tests!
Change-Id: Ic8f0a70c8222370352e63533b329c40457c0903e
When a static library A references static library B,
and app C references both A and B, we get the following symbol merging,
symbols from library B get imported twice.
We must only check that symbol references to library B are valid
when building library A. We should only merge all the symbols
when building final app C.
Change-Id: I23cba33b0901dcbb5328d9c9dfaa6a979c073c36