index: remove read_tree() progress indicator
git_index_read_tree() was exposing a parameter to provide the user with
a progress indicator. Unfortunately, due to the recursive nature of the
tree walk, the maximum number of items to process was unknown. Thus,
the indicator was only counting processed entries, without providing
any information how the number of remaining items.
Rename the Clay test suite to Clar
Clay is the name of a programming language on the makings, and we want
to avoid confusions. Sorry for the huge diff!