some bugs were causing the regression tests to fail when using
LD_PRELOAD instrumentation method

Merging mmap feature development branch back into master. Darshan
can now mmap its data structures to temporary log files at runtime to
protect against applications that do not call MPI_Finalize. Feature
can be enabled at configure time using '--enable-mmap-logs'.

A common record comparision/sort routine is now defined in
darshan-common which can be used by any modules with fixed-length
records and whose records first field is the darshan_base_record.
The comparison was also updated to sort secondarily by darshan
record identifier to resolve a potential bug in the way we have
traditionally sorted the records.

Conflicts:
	darshan-runtime/Makefile.in
	darshan-runtime/configure
	darshan-runtime/configure.in
	darshan-runtime/darshan.h
	darshan-runtime/lib/darshan-core.c
	darshan-runtime/lib/darshan-hdf5.c
	darshan-runtime/lib/darshan-mpiio.c
	darshan-runtime/lib/darshan-pnetcdf.c
	darshan-runtime/lib/darshan-posix.c
	darshan-util/Makefile.in
	darshan-util/darshan-convert.c
	darshan-util/darshan-logutils.c
	darshan-util/darshan-logutils.h
	darshan-util/darshan-parser.c

rather than using 'begin_shutdown', 'get_output_data', and
'shutdown', we combine all three into one shutdown routine.

Cleanup the structure and documenation of the code to be in sync
with the new mmap version of Darshan. In particular, I made sure
all extra mmap logic was properly ifdef wrapped so it's more clear
which portions of the code are responsible for implementing that
feature.

This interface provides some convenience functions for mapping
opaque record identifiers (could be a filename, file descriptor,
or any other type of file handle) to a corresponding runtime
structure referencing the actual file record. This runtime
structure should at least contain a pointer to the actual file
record, and can also persist arbitrary state for this record.

- memory management is now entirely handled by darshan-core for
  module records
    * when registering new records, darshan-core returns the
      corresponding buffer to write it to, rather than allowing
      module to determine this
- modules now decide whether darshan-core should track record
  names by passing either a valid name or NULL to the register
  function
    * this allows modules to register records that aren't really
      tracked by darshan-core
- only the POSIX module has been ported to new changes for this
  commit

also some code clean up to change references of record hash
to name hash to be more clear about what it is actually storing.