Add a simple sparse matrix - sparse vector test client.

This is to be expanded later and possibly merged into STINGER itself.
Oh, yes, actually save the new index in spmspv...
Include a trivial OpenMP spmspv...

Note that *both* implementations have massive bugs...
In spmspv_test, save the x pattern in a dense output vector.

Quick hack.
spmspv_test: Fix one obvious mistake in the update.
spmspv_test: Actually allocate enough space for the dense vector.
spmspv_test: simplify / fixish the cwise relative error.

OpenMP version still produces the wrong answer, which isn't bad in this
context.
Fix forgotten initialization.  Now the OpenMP example works.
A compare&swap replacement for critical sections.
Oops, another spmspv buglet.
Hackity hack on pagerank.  dpr seems to work.
Generalize PR result printing
Add basic Metis-ish file support (DIMACS10) to the server.
Have PR output appear.

The V_* macros likely are the right thing, but I'm not bothering at this
moment.
Play with PR termination thresholds.
pagerank_updating: Add different fp atomic accumulations for testing.
Actually multiply x by alpha.  Oops.
A compare&swap replacement for critical sections.
Oops, another spmspv buglet.
pagerank_updating: Add different fp atomic accumulations for testing.