Not yet supported in models (annotation=NULL), will enable in future commits.

Some refactoring and a bug fix for regenerating i/o in situations
where independent and collective i/o are used on the same file
(which is typical of hdf5 applications which use headers, etc.).

- Replay tool no longer offers bglockless prefix (ignored for POSIX
calls).
- Print workload load time on rank 0
- convert sleep functionality to use more accurate nanosleep

Note that the recorder workload now requires a parameter for the
number of ranks in the original application. the workload dump
utility has been updated to reflect this.

Hack to force replay tool to use one preallocated and initialized
I/O buffer for all I/O operations. Malloc'ing a new
(uninitialized) buffer for each I/O operation causes really poor
performance, likely due to page faults.

Darshan generates longer delays, and mpi replay tool now can be
configured to play a percentage of the overall delay.

Update recorder workload generator to obtain workload operation
parameters from new Recorder I/O traces (courteousy of Babak
Behzad). I/O offsets are now tracked explicitly in the recorder
traces, and workload file_id's are set to original execution file
descriptors.

Darshan workload generator now evenly distributes aggregators
acoss the entire rank-space. Also, individual operation sizes
are evenly distributed among aggregators, so aggregator
workloads are more evenly distributed.

- currently ugly-looking, might want to think of
  a better way to acheive this