Ported date.c (for approxidate_careful) from git.git
revision aa39b85. Trimmed out the parts we're not
using.

Added tracking configuration to the test repo's
config to support unit tests.

Removed repeated strlen's, and unnecessary loop-termination variable.

in the test repo.

Added some reflags to the test repo to support
unit tests.

Also extended the test suite to include chaining
operators, e.g. "master^2~3^4".

Supported forms:
- "^n"
- "^0"
- "^"

Still missing: all of the "^{…}" variants.

New tests for "foo^2" syntax, but they don't pass
yet. Support for chaining these, i.e.
"foo^2~3^{u}~1' is starting to shape up.

This version supports refspecs of these kinds:
- Full & partial SHAs
- Output from "git describe"
- "/refs/heads/master" (full ref names)
- "master" (partial ref names)
- "FETCH_HEAD" (named heads)

Use giterr_last() and make sure it's not NULL.

Fix MSVC compilation issue

    exp() is already defined in math.h. This leads to LMSVC complaining

    ..\..\libgit2\tests-clar\diff\blob.c(5): error C2365: 'exp' : redefinition; previous definition was 'function'

    Renaming the variable fixes this issue.

util: Fix git__isspace() implementation

These objects aren't considered as being advertised, so asking for
them will cause the remote end to close the connection. This makes the
checking in update_tips() unnecessary, because they don't get inserted
in the list.

Skip them for now. Eventually we might want to filter these out
earler.

The characters <space>, <form-feed>, <newline>, <carriage-return>, <tab>, and <vertical-tab> are part of the "space" definition.

cf. http://www.kernel.org/doc/man-pages/online/pages/man5/locale.5.html

Windows gets upset if we rename a file with an open descriptor.

Locale-aware bullshit bitting my ass again yo

Add support for diffing index with no HEAD

When a repo is first created, there is no HEAD yet and attempting
to diff files in the index was showing nothing because a tree
iterator could not be constructed.  This adds an "empty" iterator
and falls back on that when the head cannot be looked up.

Clean commit and tag messages

Enhancing the blob diffing experience

Add git_remote_add() and change signature for _new()

Add a fetch refspec arguemnt and make the arguments (name, url,
refspec), as that order makes more sense.

Helper function to create a remote with the default settings