The old syntax uses a series of Key=Value pairs, instead of
the more standard "--key value" syntax.
This is required so that the old Mendeley Desktop versions can
launch the new updater.
* Support XML scripts where the V3 script is wrapped in an <update-v3> element.
* Add some basic unit testing facilities - if we find that something more sophisticated is needed,
we can look at using cppunit, googletest or similar.
* Add a test that parsing the same script with both the old and the new structure
yields equivalent UpdateScript instances.
Prepend the install directory to the file path specified in the
<uninstall> section of the XML file to get the path of the file
to remove.
If the file cannot be uninstalled because it does not exist,
log a warning and continue.
This test compiles two 'versions' of an application,
then runs a script which creates an install directory containing
the 'old' app and a directory containing a file_list.xml update script,
a copy of the updater and a zip file containing the 'new' app.
The script then runs the updater, then runs the installed app
and checks that it is the new version.
