threads: Make the old test suite TLS aware...

Now that is_dir is calculated correctly for attr/ignore paths,
it is possible to use it so that ignoring "dir/" will properly
match the directory name and ignore the entire directory.

When building an attr path object, the code that checks if the
file is a directory was evaluating the file as a relative path
to the current working directory, instead of using the repo root.
This lead to inconsistent behavior.

When status encounters a submodule, right now it is asserting.
This changes it to just skip the file that it can't deal with.

git_refspec_transform_r assumed that the reference name passed would
be only a branch or tag name. This is not the case, and we need to
take into consideration what's in the refspec's source to know how
much of the prefix to ignore.

Those were re-added on the move. Ops!

The object cache is mostly IO-bound, so it makes no sense to have a lock
per node.

This is a MSVC-only issue. All other compilers we support work properly.

Repository re-initialization

This currently only ensures that the version of the repository format isn't greater than zero.

A non migrated yet test has been removed as well as it's mostly redundant.

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!

This had been left over from a time when I believed what the git
documentation had to say about case-sensitivity. The rest of the code
doesn't recognize this form and we hadn't noticed because most tests
don't try to get a recently-set variable but free and reload the
configuration, causing the right format to be used.

remote: add test which creates a basic remote entry in the repository configuration then loads the remote

This resolves issue #535 and issue #533.

The buffer wasn't getting freed if the last difference was a deletion.

MSVC doesn't think %zd is a valid specifier.

Don't leak when deleting or removing refs

When we remove the ref from the hashtable, we need to free the
packref.

Truncate at the slash; otherwise we get ppack-*.idx filenames.

On error, the pointer could be pointing anywhere.

Fix download segfault

transport: prevent git_remote_download() from segfaulting when being passed a lightweight remote built with git_remote_new()

This takes all of the functions that look up simple data about
paths (such as `git_futils_isdir`) and moves them over to path.h
(becoming `git_path_isdir`).  This leaves fileops.h just with
functions that actually manipulate the filesystem or look at
the file contents in some way.

As part of this, the dir.h header which is really just for win32
support was moved into win32 (with some minor changes).

Fix transport segfault

transport: prevent the transport determination mechanism from segfaulting when being passed an url starting with an unknown prefix

Going back over this, the git__removechar function was not
needed (only invoked once) and is actually mislabeled.  As
implemented, it really only made sense for removing backslash
characters, since two of the "removed" characters in a row
would include the second one -- i.e. it really implements
stripping backslash-escaped strings where a backslash allows
internal whitespace in a word.

Per issue #533, the handling of relative paths in attribute
and ignore files was not right.  Fixed this by pre-joining
the relative path of the attribute/ignore file onto the match
string when a full path match is required.

Unfortunately, fixing this required a bit more code than I
would have liked because I had to juggle things around so that
the fnmatch parser would have sufficient information to prepend
the relative path when it was needed.

Initial implementation of gitignore support

git_status_foreach() and git_status_file() will now be
gitignore aware.

After reviewing the gitignore support with Vicent, we came up
with a list of minor cleanups to prepare for merge, including:

* checking git_repository_config error returns
* renaming git_ignore_is_ignored and moving to status.h
* fixing next_line skipping to include \r skips
* commenting on where ignores are and are not included