Rename Locations functions for better consitency, and make their values
more consistent too.
Used </> rather than manually building paths. There are still more places
that manually do so, but are tricky, due to the behavior of </> when
the second FilePath is absolute. So I only changed places where
it obviously was relative.
* fsck: Check if annex.numcopies is satisfied.
* fsck: Verify the sha1 of files when the SHA1 backend is used.
* fsck: Verify the size of files when the WORM backend is used.
* fsck: Allow specifying individual files to fsk if fscking everything
is not desired.
* fsck: Fix bug, introduced in 0.04, in detection of unused data.
