partly working lustre module supporting ost mapping; shared file agg still doesn't work, and log parsing doesn't either

added filename hashing so multiple opens/closes don't create multiple lustre-mod records; added proper reducer so that shared files are flattened into a single set of counters whose values are dictated by rank 0

checkpoint of code that populates OST and MDT counts per file system--doesn't seem to work though...

Conflicts:
	ChangeLog

this calculation was inadvertently accounting for metadata time
twice. also, clarified timing descriptions for slowest unique
file perf calculations.

this functionality is helpful especially on mira/cetus where
the mpich libraries are named depending on the fortran version
and the type of compiler being used (gcc, xl, etc.).

- read and write start timestamps should record start timestamp of first
  read/write to *begin*, not start timestamp of first read/write to
  complete
- mirrors earlier fix to open timestamps

- be careful to record start timestamp of first open to start rather
  than start timestamp of first open to complete

mount information is now sorted in order of descending mount
point lengths to fix a bug in matching file names to mount
points. the longest mount point string which matches the file
name is the corresponding mount. this change requires slight
changes to the darshan-logutils API, but does not modify the
log file format

Otherwise, compile errors are generated when building an external
tool that uses the darshan-logutils api/library.

Darshan now provides debugging tips for cases where log files
are not generated.