More robust way to detect sentinel-2 level-2 images between zip files and unzipped files

[LLeiSong]

As described in the title. The related code:

sentinelPot/sentinelPot/preprocess_level3.py

Lines 694 to 699 in d838cd2

	fnames_all = os.listdir(processed_path)
	fnames_all = list(filter(lambda fname: os.path.isdir(join(processed_path, fname)), fnames_all))
	if len(fnames_all) == 0:
	fnames_all = os.listdir(processed_path)
	fnames_all = list(filter(lambda fname: fname.endswith('zip'), fnames_all))
	tile_ids = list(set(map(lambda fname: re.search("T[0-9]{2}[A-Z]{3}", fname).group(0), fnames_all)))

Thoughts:

1. List all zip files and unzipped folders
2. Compare their names
3. If they are identical, pass
4. If they are not identical, get the difference between them, give the user a warning, then pick up the ones with more files to use.