Attempt to simplify Python's BitstreamReader/Writer somewhat

They're still more complicated than I'd like
due to the need to chop up big Python longs into smaller values
properly before sending them off to the contained Bitstream objects.

A better way might be to implement bigint methods
(e.g. br->read_bigint(br, bits, bigint)) and convert Python longs
back and forth as needed.  But that'd mean either including a
bigint library or implementing one.
BitstreamReader now has a read_bigint method

This uses the stripped-down mini-gmp library that ships with GNU gmplib
in order to handle integers of any size.  The Python wrapper can
simply convert mpz_t values to Python long values as needed.
Add bigint-based BitstreamWriter methods

As with the reader, this removes a lot of clunky code
for turning Python longs into something manageable.
Remove BitstreamRecorder's split method

Now that Ogg uses getpos/setpos, I don't think anyone uses split
anymore.  Might as well take it out.
Add fix for missing FLAC SEEKTABLE block

No reason not to have one, but a lot of .flac files show up without
them.

Also fix FlacAudio's .clean() routine to have a lot less duplication.
Ensure PyLong is cast correctly when writing unsigned values

Change mpz_t fields from ints to mp_size_t values to suppress some
compiler warnings.
Fix some minor .clean() glitches
Fix Ogg FLAC's .clean() method to ignore seektables

Don't think Ogg FLACs need seektable blocks at all, really.
One can seek to the right frame just by bouncing through
Ogg pages and checking the sample index, WavPack-style.
Improve FreeDB ID calculation

This should handle a few more unusual edge cases correctly.
Add test CD for MusicBrainz from its documentation

It's not especially comprehensive, unfortunately.
Update tracklint's temp file behavior

New files are constructed alongside the old ones
so that committing the fix is a quick rename.
Reformat a lot of "if" statements to be more standard

Formatting them like:

if (something == something_else):

is just an old habit I'd gotten into over the years.  Better to do:

if something == something_else:

instead.
Reformat "while" statements to be like "if"
Add bigint options to the build and parse bitstream methods
Simplify some of the metadata __getattr__ routines

Handling slashed track number/track total fields has always been a bit of a hack.
Hopefully it's a bit less of a hack now.
Add small labor-saving function for Huffman definitions
Minor update to FLAC encoder
Remove separate write_signed_c methods

Since write_signed is implemented in terms of write, the write_signed routines will
generate errors as soon as they try to write sign bits or unsigned values
so separate write_signed_c methods aren't necessary.
Fix a DVD-A memory handling regression

This is probably the only place where BitstreamReaders are handled
in a queue-like fashion with bytes pushed in and processed bit-by-bit.
In this instance, an explicit garbage collection call keeps
the data from expanding forever.
Add BitstreamQueue as a BitstreamReader subclass

This is designed as a BitstreamReader one can dump data into in bulk
and then process on a bit-by-bit basis without having to dig into
the reader's internals.  It's similar to the buffer-based BitstreamReader
but the buffered one is meant to have a static buffer that isn't changed
after initialization.