Fixed some environment variables in the install script for Hornet.
Reorganized and documented data structures for pipeline communications.

Because these new structures use sets, functions pipe_comm()
and pipe_getAndUnblock() work out of the box, so the contents have been
uncommented.

Also, the functions to register a loop and an iteration have been removed.
This is probably something that we want to do at compile time, not at
execution time.
Clean up the modified quake source.

At this point, loop 0 and 1 call the comm primitives, which are
implemented, but they use empty data structures.The next commits should
fill in the data structures.
Style improvements and minor refactoring.

Removed old functions from the ie header (these functions don't exist
anymore).

Changed name of the niters param to create_inspector. Now it's nloops,
which is actually what it means.

Comments.
Mark last uses (ready to send data) and first uses (required data).

Only skeletons of the functions. Also, quake has been updated to use
these functions.