Is it possible to raise the number of derangements for source past 6?

[neukym]

We are running out of memory for the number of derangement we need - but higher derangements does make an improvement.

Related to:

• Delete variables after use to keep memory requirements down for gridsearch #314
• Do we need to reduce memory overhead when working with source-space gridsearch? #196
• Make sure gridsearch does not get applied to the medial wall  #166
• Gridsearch speedups TODO list  #275