glib: Add PopplerQuadrilateral boxed type

https://bugs.freedesktop.org/show_bug.cgi?id=51487
glib: Add PopplerAnnotTextMarkup class and subtypes

The subtypes are: Highlihght, Squiggly, StrikeOut and Underline.
It adds convenient methods to set/get/free quadrilaterals
necessaries for TextMarkup annotations.

https://bugs.freedesktop.org/show_bug.cgi?id=51487
glib-demo: Add support for PopplerTextAnnotMarkup

* The subtypes are: Highlihght, Squiggly, StrikeOut and Underline.
* Use ScrolledWindow for annotation properties to make room to
  show the Quadrilaterals of TextMarkup annotations.

https://bugs.freedesktop.org/show_bug.cgi?id=51487