These planning tasks are taken from the problem suites of the
International Planning Competitions (IPC). In some cases, the
numbering of the tasks does not match that of the official IPC suites,
so we recommend not using these files outside of pyperplan.

For the domains taken from IPC 2008, action costs have been removed
from the problem definitions since costs are not supported by
pyperplan.

NOTE: I've taken out all of the "unscalable" problems (e.g. PARC printer),
leaving only problem families with a single domain shared among all instances.
