Advanced search/filtering objects by characteristics, list views and keybindings

by EvilTosha for Stellarium

For now there is no tool for viewing objects with particular characteristics or types (for example all comets) inside Stellarium. My goal is to introduce a convenient interface for viewing and filtrating celestial objects, and advanced search not only by name or location, but by object's type and characteristics. Also I want to make the possibility to look through lists of most frequently used objects (planets, satellites, etc), and select by clicking. Furthermore, almost all keybindings are in use for now. I want to introduce multi-key keybindings in emacs/vim style.