Add a test case for --newuse, --changed-use, and --binpkg-respect-use.

Change-Id: I201e468c6e7cda6aa961371ad9ddc10cfab04bc7
Update dates in recently changed files.
As per bug #472104 add option --verbose-slot-rebuilds=y|n
Whitespace cleanup
man/ebuild.1: Add --verbose-slot-rebuilds option.