Summary:
- Adds `PhabricatorMenuItemView` which is a non-hacky object representing a single menu item.
- Adds `PhabricatorMenuView`, a collection of items.
- Deletes some busted/old interfaces full of garbage nonsense.
- Merges menu item styles from `aphront-side-nav-view-css` and `phabricator-nav-view-css`. These are old-style and new-style rules which got partially updated recently.
- The new-style menus have a darker background (#ececec) than the old-style menus (#f7f7f7) so some of the highlight/hover colors weren't visible. I shuffled them around but something or other might need further adjustment.
Test Plan: looked at every menu I could
Reviewers: chad
Reviewed By: chad
CC: aran
Maniphest Tasks: T1960
Differential Revision: https://secure.phabricator.com/D4036
