Date range implemented in #322.
Re video site: those `srcf` strings look almost as random as encrypted session cookies to me (yes, I know they only vary by a few bytes). I'm not sure we can reverse engineer them (any expert on exotic encodings here?), and even if we can I don't think I'll vote in favor of this feature.
Introduce options --from and --to for date range
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Fixes #320.
- Note1: I'm not 100% sure the dates must match `r'^(\d+/){0,2}\d+$'`.
- Note2: Not gonna introduce more short options, in part because `--to` clashes with `-t`, and the usual convention of making it `-T` somehow doesn't feel right.