Thread stages v0.9.0

Minor Changes

• 608783e: Show the thread's project where one icon stands for a thread — on a sidebar row,
  and in a header drawing no crumbs. The icon no longer falls back to the section
  the thread is filed under.

  A section's icon still appears where the section itself is named: beside its
  crumb in the header, and in the thread filter. What changes is the single icon
  that stands for a thread, which is now always its project's. bb's personal
  project cannot be given an icon, so a personal thread filed into a section used
  to be drawn as that section; it now keeps its own glyph.

Patch Changes

• d39bf69: Draw a section's own icon in the thread filter, in the menu and in the trigger,
  instead of the same generic glyph for every section. Sections nobody has given
  an icon keep it. The filter indicator also sits 10px from the name rather than
  4px, matching the gap a stage header leaves before its chevron.
• 56c41f0: Put sections before projects in the sidebar filter menu and quick-create
  buttons, and rename the combined filter to Sections and projects.