Added theme to rofi making use of dropdown possibility. Will create a
window spanning whole page (or less, depending on how many lines dmenu
command passes on), and dynamically resizing to number of items.
Updated script is a little more resilient, and can be used to filter by
and catch various fields, controlled with a static variable at the top
of the file for now. Still brittle, and breaks easily on bibtex file
changes.
