This redesigns the aspects of the timeline, particularly relating to
the details panel. First, selection mechanics are greatly simplified,
so items can be hovered while one is selected. Additionally, hovered
item names are now shown as part of the cursor. The details panel
now only shows details for selected items, and is moved to fill the
bottom of the screen; similarly, the timeline now fills the full width
of the screen.
Change-Id: I0acb88f898dcfd0a0327a38aa5eb995f118e1a1e
f1a1f1a650