Incorporate multiprocessing into code base

[eptrszkwcz]

incorporate multiprocessing functionality into different parts of code base - chip creation, image download, etc.

[pkerins]

It's most helpful if these issues are concrete and specific, so let's make this one about multiprocessing specifically with regards to chip creation. Notebooks now exist utilizing mproc to create chips with multiple side-by-side processes simultaneously. Consolidate these from notebooks to functions, to the extent possible. If these write to multiple separate catalogs, then include and incorporate a function for reconciling these together into comprehensive per-city catalogs.