Make all commands print git version and improve version string.

Make all commands print git version and improve version string.

Currently the format of the first line of the help output varies
between executables, for example:

	para_afh git (0.4.12.12.g15a4: spectral gravity)
	para_audioc git

This difference comes from the fact that para_afh has its own
->print_help method which uses the VERSION_SINGLE_LINE macro of
version.h while para_audioc relies on gengetopt's help output.

The latter uses the make variable PACKAGE_VERSION which gets
initialized at configure time through the second argument in AC_INIT
of configure.ac. This value is either the version number for or the
string "git".

It's a good thing to have the abbreviated git version encoded in
all executables, so this commit changes the argument of gengetopt's
--set-version to the git version string including the codename. With
the patch applied, the output of all commands looks like this if
--version was given:

	para_filter 0.4.12.12.g11d7 (spectral gravity)

To make sure things stay consistent, the patch introduces the
VERSION_SINGLE_LINE macro and changes all commands to use it instead
of open coding the version string.