Files with extension "aac" in ADTS or ADIF format are now playable.

Full credit goes to Igor Poretsky.

Change-Id: I413b34e15e5242fea60d3461966ae0984080f530

 * More tolerance to the file format variations.
 * AC3 coded files in realaudio format are now playable

Full credit to Igor Poretsky

Change-Id: Id24e94bc00623e89fb8c80403efa92f69ab1e5d7

metadata.c does not need cuesheet.h, which in apps/ and has nothing to do with
rbcodec library.

Change-Id: I914a49e8c182f5c367d7db3479c2ff39565e5f07

Synchronised with opus repo on github (https://github.com/freqmod/rockbox-opus)

Status:
* Seeking ported from speex, but fails on some cases (e.g. seek to granule 0)
* ReplayGain parsing needs to be reworked, we do vorbis-style replaygain now.
  http://wiki.xiph.org/OggOpus#Comment_Header explicitly forbids these in
  favour of R128_TRACK_GAIN tag.
* No optimisation yet, source files still nearly identical to opus upstream
* Multi-stream opus files may not be parsed correctly

Change-Id: Ia66f1027dc1d288083e3c57b2816700078376f9a
Reviewed-on: http://gerrit.rockbox.org/300
Reviewed-by: Bertrik Sikken <bertrik@sikken.nl>
Tested-by: Bertrik Sikken <bertrik@sikken.nl>

librbcodec users must provide these two files when the library is built.
rbcodecconfig.h provides configuration #defines and basic types, and
will be included by public librbcodec headers, so it must not conflict
with the user's code. rbcodecplatform.h provides various OS functions,
and will only be included by source files and private headers. This
system is intended to provide maximum flexibility for use on embedded
systems, where no operating system headers are included. Unix systems
can just copy rbcodecconfig-example.h and rbcodecplatform-unix.h with
minimal changes.

Change-Id: I350a2274d173da391fd1ca00c4202e9760d91def
Reviewed-on: http://gerrit.rockbox.org/143
Reviewed-by: Nils Wallménius <nils@rockbox.org>
Tested-by: Nils Wallménius <nils@rockbox.org>

Moved to playback.c, since it doesn't use metadata from the music file.

Change-Id: I5c3ad7750d94b36754f64eb302f96ec163785cb9
Reviewed-on: http://gerrit.rockbox.org/142
Reviewed-by: Nils Wallménius <nils@rockbox.org>

This function has been changed to rbcodec_format_is_atomic, which
doesn't require an enum from the kernel.

Change-Id: I1d537605087fe130a9b545509d7b8a340806dbf2
Reviewed-on: http://gerrit.rockbox.org/141
Reviewed-by: Nils Wallménius <nils@rockbox.org>
Tested-by: Nils Wallménius <nils@rockbox.org>

All associated files are moved to /lib/rbcodec.

Change-Id: I572ddd2b8a996aae1e98c081d06b1ed356dce222