Reduce memory usage during map creation

[JoshKarpel]

Right now, we pre-process all of the map data in memory while writing the map out to disk. The primary offender is

htmap/htmap/mapping.py

Line 433 in 5be40dd

def process_args_and_kwargs(args_and_kwargs: Iterator[Tuple[tuple, dict]]):

, but the ease of using the pre-processed data has downstream effects elsewhere.

Hopefully, we can completely remove the need for pre-processing. This would dramatically reduce memory usage during map creation.