Merged from trunk 5964:5976

Merged from trunk 5964:5976

For bug #158100, use an exact reversal of the actual merge order for
--tree output.  It's more efficient than doing 2 order calculations.

Optimize merge order calculation for --tree output when necessary.

Fix CONFIG_PROTECT_MASK support.  Thanks to piavlo <piavka@cs.bgu.ac.il>
for this patch from bug #166837.

Add missing quotes.

Add support for RSYNC_EXTRA_OPTS to webrsync (genone)

Print filename when displaying package.mask comments (genone)

[[
Ignore compiled files.

Add new feature 'preserve-libs' that injects files into $D that
- belong to a package instance that is about to be autocleaned
- are not installed by the new package instance
- are listed in at least one NEEDED file in vdb
- are not just used by other files of the package instance
As a side-effect a new file /var/db/pkg/.NEEDED is created that
contains a reversed map of the NEEDED files found in a packages dbdir.
]] (genone)

Print hostname in xterm title if sheridan is available in the
environment (genone)

svn path=/main/branches/prefix/; revision=6074