Various bug-fixes

• In cat_multimodal_sits() The masked boolean flag was actually True if the data was not masked,therefore, mask was not exported in result
• A patch was missing from !17 (closed) in pastis_dataset.py, which is required for proper handling of the S1 and S2 loading with masks
• The actual maximum day count for Pastis is 426, not 382.
• The run_all_fold.sh script from the readme was missing