Default implementation for atk_util_[add/remove]_global_event_listener

Implementing means that toolkits are not longer required to implement
those virtual methods, and is a first step to a multi-toolkit
environment.
doc: Default role is ATK_ROLE_UNKNOWN

https://bugzilla.gnome.org/show_bug.cgi?id=478587
Release 2.5.3
AtkRelation: added method that checks relationship and target

Note: the algorithm to make this search doesn't have a really
good theorical performance, but this is part caused by the
current internal structure by AtkRelationSet and AtkRelation

https://bugzilla.gnome.org/show_bug.cgi?id=672869
Release 2.5.4
Include C header information in GIR

Bug #635332.
atk.symbols: Add atk_relation_set_contains_target

This public function was added in commit a1d5ca86.
Updated Galician translations
Updated Latvian translation
Updated Polish translation
Release 2.5.91
[l10n] Update Japanese translation
Updated Brazilian Portuguese translation
Release 2.6.0
Updated Thai translation
Extend atk_add_global_event_listener in order to support signal details

https://bugzilla.gnome.org/show_bug.cgi?id=686801
Removed debug message left by mistake

Detected by Joanmarie Diggs
Release 2.7.2
introspection: merge fixes from Vala bindings

https://bugzilla.gnome.org/show_bug.cgi?id=686746
atkobject: Stop to manage SELECTABLE/SELECTED states at AtkObject

https://bugzilla.gnome.org/show_bug.cgi?id=689907