Moved treediff package back to jps-builders module.
Added methods to actualize a single path, broken compareAndApply into two
methods, added handling of non-existing hashtree, changed behavior of
listSubtree to list only files
Added mapping output root -> hashtree; added listener that notices
generated and deleted files and makes corresponding changes in the
corresponding hashtrees; added OutputRootIndex holding all output roots of
the project
Wired up outputroot-to-hashtree-mapping-changing listener in runBuild() of
IncProjectBuilder, changed upload and download actions so that
compression, uploading, downloading and updating of output happens per outputroot