Finished up the automatic recovery from stale lock files. Turns out git has quite a few lock files; the assistant handles them all.

Improved URL and WORM keys so the filenames used for them will always work on FAT (which has a crazy assortmeny of illegal characters). This is a tricky thing to deal with without breaking backwards compatability, so it's only dealt with when creating new URL or WORM keys.

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I think my next step in this disaster recovery themed month will be adding periodic incremental fsck to the assistant. git annex fsck can already do an incremental fsck, so this should mostly involve adding a user interface to the webapp to configure when it should fsck. For example, you might choose to run it for up 1 hour every night, with a goal of checking all your files once per month. Also will need to make the assistant do something useful when fsck finds a bad file (ie, queue a re-download).