Cope with Debian's new Java version numbering scheme
"0install select" now always does a fresh selection

Before, if it was used with an app and no additional requirements, it just
showed the current selections. But now, use "0install show" for that.

For apps, it now shows what changed too, and prompts you to use "0install
update" to save the changes if either the requirements or the selections
changed (before, it only prompted if the requirements had changed).
Use existing requirements in "0install select app"

Before, we only took the URI from the app when selecting and ignored any other
saved requirements.
Add support for --user to freedesktop.org config
Work around for another PyGTK GC bug

Reported by Tim Cuthbertson.
Fixed error message when an interface doesn't exist

Was broken by a99b0fad2d111. Reported by Tim Cuthbertson.
Removed "alias:" resolution from model (handled by .NET code)
Fixed missing close in "0store optimise"

Was leaking file descriptors for old-style "sha1" manifests.
Added <for-each> syntax for arguments

This makes it possible to expand an environment variable into a list of arguments.

e.g.

      <for-each item-from="EXTRA_OPTIONS" separator=" ">
	<arg>-X</arg>
	<arg>${item}</arg>
      </for-each>
Handler.report_error shows the stack-trace with --verbose
Improved diagnostics to show when a candidate had unsatisfied restrictions

When listing rejected candidates, check to see whether they have dependencies
which conflict with a selected implementation, and show the restriction causing
the problem if so.
Added an explicit dependency on python-gobject

This is needed on Fedora to prevent us running 0install with Python 3 when
we only have the Python 2 version of python-gobject.

It will also be needed on OS X to make sure we don't mix the native version
of Python when only the MacPorts Python has python-gobject.

Requested by Tim Cuthbertson.
Detect .NET Framework installations on Windows as <package-implementation>s
Merged .NET framework detection
Merged changes from master