Added a --version parameter

Works similarly to 'plumbing getlevel', but provides something human-readable
and information more relevant to humans.
Added several debugging messages
Update checksums during package construction

The new triggers can alter (and even remove) files after the initial copying
has been performed. So in order to make sure that the checksums are correct we
need to do the checksumming very late instead of very early.
Make sure that the destination, not the source, is checksummed
Make sure $dir is absolute, and don't die on "broken" symlinks in legacyInstallPackage
Added ipv6(ish) support
Fixed category SQL generation

API got changed to generate an folder_id IN list instead of explicitly building
a large OR statement. The changed method name reflects this, and its users
have been changed accordingly.