Test scripts naming

  Hello,

  I think we should do something about the test script names. Currently
it appears almost like the scripts are basically unordered, and the
digit you increment is chosen mostly randomly. Also, the "freeform"
field after the test number is not as informative as it could be. What
are the rules you use for naming the testcases? Could you please
document it in the README?

  I'd propose:

  First digit: "family", e.g. the absolute basics and global stuff (0),
the basic db-side commands (read-tree, write-tree, commit-tree), the
basic working-tree-side commands (checkout-cache, update-cache), the
other basic commands (ls-files), the diff commands, the pull commands,
exporting commands, revision tree commands...

  Second digit: the particular command we are testing

  Third digit: (optionally) the particular switch or group of switches
we are testing

  Freeform part: commandname-details

  How would I rename the current scripts?

t1000-checkout-cache.sh -> t2000-checkout-cache-clash.sh t1001-checkout-cache.sh -> t2001-checkout-cache-clash.sh t0200-update-cache.sh -> t2010-update-cache-badpath.sh t0400-ls-files.sh -> t3000-ls-files-others.sh t0500-ls-files.sh -> t3010-ls-files-killed.sh