Preparation for merging tiles

[piyushrpt]

• Consistency checks that pixels in overlapping tiles are only offset by integer cycles
• Bulk pairwise offset estimation similar to snaphu tiler
• Number of typing related fixes
• Dependent on Adding EMCF solver #10 and Add regular and density-based tilers + Link model grid search #11
• More to come

[gmgunter]

Sorry for the delay. Looking good overall.

Detailed comments below. The main things are:

1. There are a few places where the documentation could use some improvement
2. The ability to avoid re-processing intermediate files that were previously generated is handy, but IMO it should be an option that users must opt into rather than being always enabled.

We could address the comments in a subsequent PR(s) if you want. Feel free to merge this one whenever you're ready since there's another open PR that depends on it.