k Augment points_t to include cyclen, only if nell model (cmt that)

k Populate initial cyclen in identity/urandom init, only if nell model

k #def'd check routine (x->cyclen vs. get_cycle_length(x))
k undef it after verification and profiling!

k Modify Delta_Nell in energy.c, only for nell model
k Modify are_in_same_cycle.

k Update in metro.c on accept, only for nell model.

? Move marks into point_t?

? rename c, cworm, etc. to v1, v2, v3, ...

k profile
k compare RVs side by side

k archive today's tree
k write cclen over cworm