Add support for log weights #510
Description
Feature description
We know we don't do particle filtering the textbook way, and we know (or at least have decently informed hypotheses, see #153 and #187) as to why. Would those heuristics be necessary if we had infinite precision numbers? I suspect they wouldn't be. And, sure, we can't have infinite precision, but we can move to the log domain, compressing weights' dynamic range and replacing multiplication for addition.
Others have had the same thoughts in the past, https://onlinelibrary.wiley.com/doi/10.1155/2018/5763461.
Implementation considerations
A LogWeight type may help us map expressions to the proper arithmetic and normalization operators so that we don't need specific models for log and non-log weights.