This new approach allows filtering out checks from the default set that are
not appropriate for a command, rather than having to list every check
that is appropriate. It also reduces some boilerplate.
Haskell does not define Eq for functions, so I had to go a long way around
with each check having a unique id. Meh.
These were a mistake, they make the type signatures harder to read and
less flexible. The CommandSeek, CommandStart, CommandPerform, and
CommandCleanup types were a good idea, but composing them with the
parameters expected is going too far.
stop changing gitattributes on init
create git-annex branch on init
ugly special case for init in a bare repository goes away, yay!
git annex init is also faster, at least in a large existing repo, as
it does not need to run the slow 'git add'
