Fix parallel installation for API version 0.5

Signed-off-by: Roberto Guido <bob4job@gmail.com>
Add more entries to .gitignore

Signed-off-by: Roberto Guido <bob4job@gmail.com>
added ability to add SoupSession features (gzip compression and cookies)
Reformatted previous patch
Add basic support for GObject Introspection.

Following instructions at:
https://wiki.gnome.org/GObjectIntrospection/AutotoolsIntegration

More work is needed: Many warnings are generated by g-ir-scanner, and
several methods are not introspected.

Signed-off-by: Roberto Guido <bob4job@gmail.com>
feeds-publisher.c: Fix erroneous comment header

Comment header of the GrssFeedsPublisher::delete_subscription signal
said "new_subscription" instead of "delete_subscription".

Signed-off-by: Roberto Guido <bob4job@gmail.com>
Fix many warnings from g-ir-scanner

- Only introspect public header files and C files implementing these
  public classes.

- Include used libraries as --include directives to g-ir-scanner.

- When running g-ir-scanner, add environment variable GIFLAGS so we can
  easily add flags like --warn-all when needed.

Signed-off-by: Roberto Guido <bob4job@gmail.com>
Add lots of GObject Introspection annotations.

Also fixes a bug in feed-channel.c:
grss_feed_channel_get_cookies returns a GSList, not a GList.

Signed-off-by: Roberto Guido <bob4job@gmail.com>