src/sndfile.hh: initialize all member variables

Signed-off-by: Erik de Castro Lopo <erikd@mega-nerd.com>
Fix detection and usage OpenBSD's <sndio.h>.
tests/ : Fix warnings from clang 3.5.
Update .gitignore for CMake artifacts.
CMake : Build system nears parity with autotool build system.

Specifically, it can now build the shared library (without Ogg/Vorbis
or FLAC support) and the programs as well as building and running
the tests using 'make check'. This new CMake build system has a single
top level build description and on Unix, by default generates a non-
recursive Makefile (unlike the existing autotools build system).

I dedicate this commit to Peter Miller (pmiller) who died in the early
hours of 2014/07/27 after a long illness. Peter was the author of the
paper "Recursive Make Considered Harmful":

    http://aegis.sourceforge.net/auug97.pdf

This paper was the inspiration for the build systems for the Linux
kernel, the Glasgow Haskell Compiler and many other projects.

Peter was also the author of a Make replacement program Cook:

    http://miller.emu.id.au/pmiller/software/cook/

Peter was a great friend, a great work colleague and an extremely
skilled and knowledgeable software engineer.

Goodbye my friend. #commitforpmiller
CMakeLists.txt : Generate tests/test_wrapper.sh during configure.

Plus other minor cleanups.
configure.ac : Fix chmod of Scripts/build-test-tarball.mk.
More fixes for HAVE_SNDIO_H changes.
CMakeLists.txt : Use bash to run test_wrapper.sh.
Purge redundant file binheader_readf_check.py.
configure.ac: Fix detection of MinGW

This is more consistent with other checks in the file and fixes #75.

Signed-off-by: Erik de Castro Lopo <erikd@mega-nerd.com>
AUTHORS : Add contributors.
src/ : Add more checks for suported channel counts.
src/common.h : Increase SF_MAX_CHANNELS from 256 to 1024.

Closes: https://github.com/erikd/libsndfile/issues/78
src/sndfile.c : Fix sfinfo.frames file on SFM_WRITE.

When opening a file in SFM_WRITE mode where the output is a pipe,
the sfinfo.frames value was coming back with strange values. The
fix is simply to make sure it get set to zero.

Closes: https://github.com/erikd/libsndfile/issues/77
Fix some typos.

Closes: https://github.com/erikd/libsndfile/pull/79
Signed-off-by: Erik de Castro Lopo <erikd@mega-nerd.com>
src/flac.c : Remove un-needed code.

The code was calling FLAC__stream_decoder_seek_absolute () immediately
followed by a call to FLAC__stream_decoder_get_decode_position (), the
result of which was immediately thrown away.

Reported-by: Mario Lang <mlang@delysid.org>
Minor CMake files.

* CMake now fails of CMake/config.h.in doesn't exist.
* Command './autogen cmake' now generates CMake/config.h.in.
src/common.h : Double value of SF_FILENAME_LEN to 1024.

Closes: https://github.com/erikd/libsndfile/issues/81
src/sndfile.c : Return an error if the file path is too long.