role: Add media (audio and video) roles

https://bugzilla.gnome.org/show_bug.cgi?id=711558
atkdocument: deprecation of some methods

atk_document_get_document, atk_document_get_document_type and their
equivalent virtuals were deprecated. Documentation properly updated.

At least atk_document_get_document_type seems to be announced as
deprecated since a long time ago. At least firefox code (in form
of comments) mention that. The case of atk_document_get_document
seems worse, as it doesn't makes too much sense. None of them
are used at at-spi at all.
doc: improve documentation of AtkAttribute and AtkAttributeSet
Updated Spanish translation
doc: improve ATK_TEXT_ATTR documentation
state: add ATK_STATE_CHECKABLE and ATK_STATE_HAS_POPUP

https://bugzilla.gnome.org/show_bug.cgi?id=712576
https://bugzilla.gnome.org/show_bug.cgi?id=712581
roles: new ATK roles for ARIA roles (plus rating)

https://bugzilla.gnome.org/show_bug.cgi?id=712586
Release 2.11.2
Updated Greek translation