other simulation variables to "save"

[gonsie]

what global variables should be saved to the checkpoint-readme file? The variables don't need to be read by ROSS, just by any user of the checkpoint.

[gonsie]

Random number generator information:

• g_tw_rng_seed
• g_tw_nRNG_per_lp

Note that these variables are truly global (should be the same on each mpi rank) and are not needed to read a checkpoint (each LP saves its own RNG state).

[gonsie]

If the lamport path / critical path information is added to LP and events, then this information will need to added to the checkpoints. Along with other PE-level statistics. The statistics API should really be overhauled.