HyP3 isce3 v0.3.1

Changed

• With --subset, the ECMWF troposphere weather models are now streamed and cropped to the AOI plus a 1-degree buffer (new hyp3_isce3.crop_tropo module) instead of downloading each ~2 GB global file. The cropped file is ~0.5 MB and gives identical RAiDER delays.

Fixed

• --subset crops now derive the frequencyB range window from frequencyA's so both bands start at the same slant range. isce3's split-band ionosphere step decimates frequencyA offsets onto frequencyB, so independently windowed bands misregistered frequencyB by over a resolution cell, decorrelating it and leaving the ionosphere filter mask (bit 24 of the GUNW mask layer) speckled.
• --subset crops now snap their origin to both the crossmul and phase_unwrap looks (and frequencyB to its own unwrap looks), so every multilook grid lines up with a full-frame run.
• --subset crops now crop inputDataExceptionMask with the image window and set identification/isFullFrame to False.
• Corrected copy-pasted or outdated docstrings in process.py and __main__.py.
• Updated ISCE3 version and included provisional collection for GUNWs.