properties-dialog: Use headerbar and improve spacing and borders

https://bugzilla.gnome.org/show_bug.cgi?id=739836
css: Fix border-radius of thumbnails

Use 0 instead of 0px.

https://bugzilla.gnome.org/show_bug.cgi?id=739836
libdocument: adding class EvAnnotationTextMarkup

Implementing the (trivial) class
EvAnnotationTextMarkup and fixing a typo.

https://bugzilla.gnome.org/show_bug.cgi?id=583377
libdocument: adding annotation highlight

Implementing the type and a method to create
highlight annotations.
pdf: Create highlight annotations for existing annotations in document

Implementing the type and a method to create
highlight annotations.

https://bugzilla.gnome.org/show_bug.cgi?id=583377
shell: Show highlight annotations in the sidebar

https://bugzilla.gnome.org/show_bug.cgi?id=583377
libdocument: Use a common annotation type for text markup annotations

And a type property for the different kinds of text markup annotations