It was a hidden static variable of the policy engine, which would've
been a problem in a multi-port device.  Now it won't be anymore.

Apparently one of the threads was using too much stack space??  This
will require investigtion later, but for now increasing their stack
space fixed some weird problems I was having with this patch.

It isn't used there, so it doesn't need to be included.

It's not general-purpose PD Buddy code, but rather PD Buddy Sink code.
Therefore it gets the pdbs namespace.

The code compiles again, and it seems to work as it did before.  There's
still a lot to do (we still have a mess of globals), but the PE
correctly calls the new DPM functions via the list of callbacks in the
configuration object.

These new headers define structs for configuring the library.  They're
currently unused, and some function prototypes no longer match.

For now, the new <pdb.h> file only has a function to start the library,
based on the old start_pd function from main.c.  It'll eventually be all
a user needs to include, but there's a lot more refactoring to do.

/!\ 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.

There are now a few extra lines in the Makefile that make the PD Buddy
firmware library's makefile get included, and the variables it defines
get used.  There's no code to compile or include yet though.

When we receive a GotoMin message, we immediately go to lower power
before entering the PE_SRC_Transition_Sink state.  Therefore, the call
to pdb_dpm_output_set was redundant in this case.  Now the call isn't
made in this case, removing the redundancy.  This also leads somewhat
into the design of the new library.

The "storage" source code files contained lots of stuff with "config" in
the name, but nothing named "storage".  This was unlike every other part
of the firmware, so I renamed the files to "config".

Now the call to fusb_get_typec_current is made in the policy engine,
then passed to pdb_dpm_evaluate_typec_current.  This is more consistent
with pdb_dpm_evaluate_capability, improving the PD Buddy DPM API.
That's right, I'm thinking about API design now for when I split the
code into a library and application.

Now that we cache the configuration location in the configuration code
itself, we don't need to cache it elsewhere.  This makes the DPM code
for evaluating Type-C Current much cleaner.

Until now, the valid configuration object's location was not stored, so
it had to be looked up every time pdb_config_flash_read was called.  Now
the valid object's location is stored in config_cur, which is updated
every time the configuration's location changes.  This means that
pdb_config_flash_read only has to do the full routine the first time
it's called, or after pdb_config_flash_erase is run.  Now other parts of
the configuration won't have to cache the location themselves anymore.

The cfg_set variable was not necessary after all, since testing if
cfg == NULL works just as well as testing if !cfg_set.  Actually a bit
better, since it prevents a null dereference we did by mistake before.
I should find out if the null derefernce hurts anything, because if it
does I should make a patch to the 1.1.x series to fix it.

The received Type-C Current advertisement is now kept in a global
variable which can be read by the command shell.  When there are no PD
capabilities but there is Type-C Current, the typec_virtual PDO is
reported as the one and only PDO.

Not a real PDO, the typec_virtual PDO will be used to report the
advertised Type-C Current when Power Delivery is not available.

This commit adds support for the firmware version extension, as
described at http://www.fwupd.org/developers S. USB Firmware Version
Extensions.  This gives a new way of reading the firmware version, which
is apparently preferred by fwupd.  I'd kinda like to be able to use
fwupd to update the device's firmware starting with the new minor
version, so this is a first step towards that.

There will be a version 1.2 eventually, hopefully bringing support for
some new PDO(s).

The API for the new features is stable, and the implementation seems
complete and bug-free.  I can't see any reason not to release, so here
we go!

Each field's name and meaning is listed now, and the unsupported types
are no longer listed as if they are supported.  As always, I'd like to
support variable and battery PDOs, but I need hardware that sends them
to add such support.

Since the spec says we Shall request no more power than we actually
need, we were violating the spec whenever the output was disabled in
Setup mode.  This commit fixes that, requesting low current at 5 V when
the output is disabled.

We do play a little fast and loose with the MAX_CURRENT field, but
that's hard to avoid in a device like this.  Well, we could always set
it to 5 A in Setup mode to be safe, but that's not necessarily right
either.  At least it's still honest in Sink mode, which I consider more
important anyway.

We don't need to update the source's capabilities when setting our
output state.  Now we just send a new Request.  For now, that request is
redundant, but soon I want to make the Sink request less current when
the output is disabled.  Whether the voltage should be the same or
always vSafe5V in that case, I haven't decided yet.  There are
advantages to each, but the difference is so minor in terms of using the
device that I don't see a reason to let the user choose, which of course
puts the decision on me.