Basic authentication for http and winhttp

Correctly parse tags lacking a description

Fix compilation for mingw32 and cygwin

inet_pton is available only in windows vista or later,
fixed the issue by reimplementing it using WSAStringToAddress

fetch: Write packs to the ODB instead of directly to disk

Bail out of remote loading if the URL would be NULL

Apparently git_remote_list() includes even remotes for which git_remote_load() would fail. Sorry @nulltoken, false alarm.

This reverts commit f358ec14.

CC @nulltoken

Fix state when HEAD is not detached

Let the user grab the packfile as it's being written

This fixes a crash from attempting to invoke git__strdup() against NULL.

Fix bytes_received in fetch tests - we weren't calling the callback

This fix makes libgit2 capable of parsing annotated tag objects that lack
the optional message/description field.
Previously, libgit2 treated this field as mandatory and raised a tag_error on
such tags. However, the message field is optional.

An example of such a tag is refs/tags/v2.6.16.31-rc1 in Linux:

$ git cat-file tag refs/tags/v2.6.16.31-rc1
object afaa018cefb6af63befef1df7d8febaae904434f
type commit
tag v2.6.16.31-rc1
tagger Adrian Bunk <bunk@stusta.de> 1162716505 +0100
$

Initial implementation of diff rename detection

Free conflict index entries on removal

Prefer GetLastError() for GITERR_OS on Win32

Improve docs, examples, warnings

Some more changes to the Index API

This improves docs in some of the public header files, cleans
up and improves some of the example code, and fixes a couple
of pedantic warnings in places.

Why Apple, why?