first phase resolves referenced build URIs as each build is loaded
second phase resolves references without an explicit project ID
(this requires the whole structure to be known and this isn't available during the first phase)
setting resolution is unchanged (done after both phases)
finish alias support
better project printing in 'projects'
completion support for 'help'
resolve URIs in ProjectRef against base URI of defining build in keys and project relations
resolve base directories and record build URI in BuildUnit
preserve relative paths in File to URI conversion for later resolution
Mark Harrah