Handling Circular and Re-entrant Library Imports

Hi,

The algorithm in the section "Handling Circular and Re-entrant Library
Imports" does not seem to take into account the fact that p:declare-step
and p:pipeline can contain import statements as well.

Since the algorithm is primarily URI-based, the spec should probably say
something about how to represent the nested p:declare-step/p:pipeline as
URIs, at least conceptually.

Regards,
Vojtech