Now the user-visible FUSB302B functions all take a struct
pdb_fusb_config * as a parameter.  The static functions don't use it
yet, but at least the public API of this code is in its finished state.

/!\ BROKEN BUILD /!\

This commit moves the library code to the library directory.  This
causes the firmware to not compile.  A few changes were made to reduce
the nubmer of errors, but some errors just aren't going to go away until
I go ahead with the planned changes.

I think so, anyway.  Testing with a heat gun didn't result in the Sink
resetting itself, so I'm not confident that I understand the FUSB302B's
over-temperature sensing mechanism.

I must point out though that I'm not confident that this
over-temperature protection is even useful.  The PD Buddy Sink doesn't
get hot on its own, and if it did, it might not even be from the device
it's powering, making a hard reset useless.  The spec says that we Shall
implement over temperature protection though, and that we Shall send a
Hard Reset message when it engages, so even though I take issue with the
requirement, I'll try to do what the standard says I Shall.

There are still a few things that the standard says we Shall do and we
don't, but it Works For Me™.  I haven't implemented anything with
regards to GiveBack support, but that doesn't matter just yet.  Our
handling of VDMs isn't quite right either.  Anyway, it successfully
negotiates with so-called Split PDO power supplies, which is more than I
can say about some commercial products.