Add better default masking for `timeseries` results

[scottstanie]

• for snaphu-like unwrapped results, need to combine or redo connected component labels
• complete the PR for writing out residuals from the timeseries inversion
• add some recommended mask (maybe from a command) to combine temporal coherence/similarity
• rasterio.errors.RasterioIOError: Read or write failed #540 (comment)