The plugin was not destroying a hash table properly, causing
segfaults. Also, the workload did not close open files or
directories, causing an error on the number of open file
descriptors.

Darshan reports zero-valued timestamps as negative values, so
add check to set these timestamps to zero if they are negative.

Darshan and recorder workloads have temporary debug parameters that
are no longer used and can be removed.

The darshan workload generator now checks that the log version
is at least 2.03. This is due to a bug with how timestamps are
reported in prior versions.

Workload API now defines a function for retrieving the rank count
of a workload. Currently, only darshan workload implements this.
Will work on bgp workload and recorder later.

updates to i/o lang: modifying i/o lang-codes workload API to return correct offsets according to the ranks