add disc_generic.c to distribution

Again a problem distributing for Autotools and Cmake.
This one wasn't catched by testing the distribution
on "supported platforms".
set version to 0.4.1

Again, there is no change in the library itself,
but pushing the patch version doesn't hurt
and reduces confusion later on.
mention which versions are new in the API doc
Added a discid_read_sparse() method.

This allows faster reading of  a disc when some features, e.g. ISRC or MCN, are not required.
Added example for discid_read_sparse()
The features flag parameter should be an unsigned int.
correct API doc for features
correct features_length doc
fix libtool comments in configure.ac
Small documentation fixes.
By default discid_read will use all available features.
Updated existing examples to use discid_read_sparse(), removed separate example discid_sparse.c.
In C89 and Ansi C variable declaration has to be at the beginning of a scope block.

Required to build in Visual Studio out of the box.
Fixed DLL version information.
Add Visual Studio files to .gitignore.
Add build results to .gitignore.
Fixed encoding information in DLL metadata.
Merge remote-tracking branch 'phw/read_sparse'

See LIB-29 and pull request #11
better coding style in darwin disc_read

Only fixing that one function, since it was recently changed a bit,
so we have consistent style at least in the function.
Other fixes should be made with other code changes.

I am not necessarily fond of tab indentation, but that is
what the main files are using.
update AUTHORS and ChangeLog for read_sparse