Fix compilation of test.c
Fix introspection problem

gnome-pocket/gnome-pocket.h:51: Warning: GnomePocket: gnome_pocket_new: return value: Unresolved type: 'GnomePocket*'
Namespace "Pocket/POCKET" constants properly
Mark a few struct members as private
Make gnome_pocket_get_type() static
Add API docs for a couple of GnomePocket functions
Fix assertion when run in gir-scanner
Work-around introspection bug

GIR fails when the namespace has the same name as one of the objects.

https://bugzilla.gnome.org/show_bug.cgi?id=628496