https://bugzilla.gnome.org/show_bug.cgi?id=650885

Signed-off-by: David Zeuthen <davidz@redhat.com>

g-ir-scanner does not allow a space between the : and the
section name.

Since the previous commit, the g_unix_connection_send_credentials() /
g_unix_connection_receive_credentials() functions now also works on
FreeBSD since GUnixCredentialsMessage now works there.

The main idea is that the g_unix_connection_send_credentials() /
g_unix_connection_receive_credentials() functions are the "main" API
for getting credentials (one way or the other). So it's better to
avoid advertising where it is currently implemented.
Signed-off-by: David Zeuthen <davidz@redhat.com>

 - Make GCredentials instance and class structures private so it can't
   be subclassed and we don't have to worry about ABI compat
   issues. This also allows us to get rid of the GCredentialsPrivate
   struct.

 - Add a GCredentialsType enumeration that is used whenever exchanging
   pointers with the user. This allows us to support OSes with
   multiple native credential types. In particular, it allows
   supporting OSes where the native credential evolves or even changes
   over time.

 - Add g_socket_get_credentials() method.

 - Add tests for g_socket_get_credentials(). Right now this is in the
   GDBus peer-to-peer test case but we can change that later.

 - Move GTcpConnection into a separate gtk-doc page as was already
   half-done with GUnixConnection. Also finish the GUnixConnection
   move and ensure send_credentials() and receive_credentials()
   methods are in the docs. Also nuke comment about GTcpConnection
   being empty compared to its superclass.
Signed-off-by: David Zeuthen <davidz@redhat.com>

fixes a build issue

Instead, make it always send the current credentials.

Make sure all unix-specific apis are marked as such.

Also move send_credentials() and receive_credentials() to
GUnixConnection. This code might change, discussion is still ongoing
in

 https://bugzilla.gnome.org/show_bug.cgi?id=617483.

Currently, to implement cancellability correctly, all synchronous
calls to GSocket must be preceded by a g_socket_condition_wait() call,
(even though GSocket does this internally as well) and all
asynchronous calls must do occasional manual
g_cancellable_is_cancelled() checks. Since it's trivial to do these
checks inside GSocket instead, and we don't particularly want to
encourage people to use the APIs non-cancellably, move the
cancellation support into GSocket and simplify the existing callers.

http://bugzilla.gnome.org/show_bug.cgi?id=586797

Lots of pedanic changes.

Bug #583206.

The whole protocol name thing is pretty weird. The getprotobyname functions
seem to only specify one mapping for name <-> ids, so all families/types
must use the same values. Plus the values used for the protocols are
standardized by IANA, so are always the same.

So, we drop using names for protocols, intead introducing an enum with
a few commonly availible and used protocols.

This imports the network APIs into the gio reference docs, and cleans
up a bunch of gtk-doc warnings and documentation issues.