Fixed|Client|InFine: Finale/intermission stretch scaling, HOM around view

This commit addresses various issues related to stretch scaling:

- "rend-finale-stretch" was not being applied at all, presumably due
  to the unfinished UI2/InFine refactoring. Now that the UI2 drawer
  is exclusively used for drawing InFine (with the old engine UI gone),
  we can just apply a bordered projection there and not worry about
  what kind of UI page is actually being drawn.

- Scissor was not disabled immediately after ending a bordered
  projection, meaning that a mask applied at the time would not
  be visible.

- Color buffer clearing is needed if there are finales to draw that
  aren't stretched.

IssueID #1719