Allow Operator to reduce depletion chain from geometry
Allow Operator to reduce depletion chain from geometry

A new parameter, reduce_chain, can be used to instruct the
operator to create a smaller depletion chain. The geometry is
used to find all nuclides in burnable materials. The argument
can be a boolean, or a non-negative integer. A value of True
indicates no depth for following the paths, while an integer
can be used to directly specify the depth.

walshjon/openmc,smharper/openmc,amandalund/openmc,amandalund/openmc,liangjg/openmc,mit-crpg/openmc,amandalund/openmc,mit-crpg/openmc,walshjon/openmc,walshjon/openmc,paulromano/openmc,liangjg/openmc,liangjg/openmc,walshjon/openmc,paulromano/openmc,liangjg/openmc,mit-crpg/openmc,smharper/openmc,mit-crpg/openmc,shikhar413/openmc,smharper/openmc,paulromano/openmc,shikhar413/openmc,smharper/openmc,shikhar413/openmc,amandalund/openmc,paulromano/openmc,shikhar413/openmc