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

We force stat to be a stat64 structure, so we can and should put all
64 bits of the size in st_size.

off_t is always 32 bits in Windows, which is beyond stupid, but we just
don't care anymore because we're using `git_off_t` which is assured to
be 64 bits on all platforms, regardless of compilation mode. Just
ensure that no casts to `off_t` are performed.

Also, the check for `off_t` overflows has been dropped, once again,
because the size of our offsets is always 64 bits on all platforms.

Fixes #534

In the main loop we peek to see what kind of line the next one is. If
there are multiple newlines before the end of the file, the eof marker
won't be set after we read the last line with data and we'll try to
peek again. This peek will return LF (as it pretends that we have a
newline at EOF so other function don't need any special handling).

Fix cfg_getchar so it doesn't try to read past the last character in
the file and config_parse so it considers LF as EOF on peek (as we're
ignoring spaces) and sets the reader's EOF flag to exit the parsing
loop.

This contains fixes for several issues discovered by MSVC and
by valgrind, including some bad data access, some memory
leakage (in where certain files were not being successfully
added to the cache), and some code simplification.

This gets rid of the crazy macro version of git_path_walk_up
and makes it into a normal function that takes a callback
parameter.  This turned out not to be too messy.

The last checkin accidentally broke dir_for_path by propogating
the dirname return code even when there was no error.

This fixes issue 532 that attributes (and gitignores) could not
be checked for files that don't exist.  It should be possible to
query such things regardless of the existence of the file.

Adds support for .gitignore files to git_status_foreach() and
git_status_file().  This includes refactoring the gitattributes
code to share logic where possible.  The GIT_STATUS_IGNORED flag
will now be passed in for files that are ignored (provided they
are not already in the index or the head of repo).