Add timeline web UI to set tag filter and match style.  Still not 100%.  (1) Now that more than one text entry is on the page, pressing enter does not trigger a submit [Firefox ESR 10.0.12], (2) electing "Related" causes Tag Filter to blank, (3) entering a tag filter while "Related" is selected causes "Related" to be deselected, (4) possibly too much clutter, and (5) definitely too much clutter if combined with any future expansions.  (1) is due to the lack of a submit button.  (2) and (3) are a bad interaction between the t=/r= dichotomy and the design of style_submenu_entry().  (4) maybe could be addressed by changing "Related"/"Branch Only" and "Without Files"/"With Files" to checkbuttons, but style_submenu_checkbox() was never actually implemented.  (Probably also want "Unhide" to be a checkbox.)  For (5) I have in mind letting the admin define a project-specific list of preset filters.