Fix arguements selection of 'ogit clone'
Improve pretty printing of Git objects
Fix the test suite
Remove the children lexical ordering invariant.

It seems than the Git implementation does not ensure it properly anyway.
Cosmetic changes
Lwt_io.read ~count does not guarantee to read exactly [count] bytes

So use Lwt_io.read_into_exactly instead. This is critical to get the right line size otherwise we were seeing random errors (which were corresonding to random sequence of bits being interpreted as a line size).
Replace a Hashtbl.replace by Hashtbl.add.

Not sure it's worth, but should be a bit less expensive.
Fix space leak