A more compact bookmark display

* Annotations can be disabled from being shown
* Buffer name only shown by bm-show-all, not by bm-show
* Buffer name and line number column is only as wide as it needs to be
* White space is stripped when showing the bookmarked text

FWIW bm-tests.el is passing for me here using Emacs "24.3.1" (built from emacs-24 Git branch as of a couple days ago), unofficial Mac port.