Make Helpify output auto-closing XML tags in more places.

hiutil on 10.10/Xcode 6.1 complains about them otherwise.
Index the main help page minimally.

hiutil on 10.10/Xcode 6.1 complains about the meta tag otherwise, with an entirely unhelpful message.  I really don’t want it to be indexed at all; it’s just a table of contents.
Better indent the <html> tag in Helpify.
Drop support for Mac OS X 10.6 and OS X 10.7.
Fix failure to set dock icon color on launch.
Code sign frameworks as they’re copied into Shroud’s bundle.

Updates for Gatekeeper 2.