glib: Add PopplerQuadrilateral boxed type
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.
glib-demo: Add support for PopplerTextAnnotMarkup
glib-demo: Add demo for markup text annotations (WIP)
glib-demo: Add text markup annotations (highlight)