Fix a doxygen typo ("@para" instead of "@param") in odb.h

Fix a few minor typos in the documentation of the GIT_ERROR codes.

Temporary files when doing streaming writes are now stored inside the
Objects folder, to prevent issues when moving files between
disks/partitions.

Add support for block writes to the ODB again (for those backends that
cannot implement streaming).

MSVC doesn't swallow that.

In the same spirit that git_repository_lookup is no longer available,
add wrappers so the users don't have to cast when closing their
objects.

Signed-off-by: Carlos Martín Nieto <cmn@elego.de>

Add remove_placeholders() test helper function which recursively removes marker files from a directory structure

We have removed the hooks folder because it takes a lot of space

The folder creation is now decorrelated from the recursive parsing of the source tree structure.

Those functions now return prettified rooted path.

see https://github.com/libgit2/libgit2/issues#issue/84

When the system temporary folder is located on a different volume than the working directory into which libgit2 is executing, MoveFileEx() requires an additional flag.

git_time_t is defined as a signed 64 integer. This allows a true predictable multiplatform behavior.

Thanks to Carlos Martín Nieto for spotting this.

Free the ref_file buffer at the end of the function also on
success. This fixes a small memory leak.

Hey. Apologies in advance -- I broke your bindings.

This is a major commit that includes a long-overdue redesign of the
whole object-database structure. This is expected to be the last major
external API redesign of the library until the first non-alpha release.

Please get your bindings up to date with these changes. They will be
included in the next minor release. Sorry again!

Major features include:

	- Real caching and refcounting on parsed objects
	- Real caching and refcounting on objects read from the ODB
	- Streaming writes & reads from the ODB
	- Single-method writes for all object types
	- The external API is now partially thread-safe

The speed increases are significant in all aspects, specially when
reading an object several times from the ODB (revwalking) and when
writing big objects to the ODB.

Here's a full changelog for the external API:

blob.h
------

	- Remove `git_blob_new`
	- Remove `git_blob_set_rawcontent`
	- Remove `git_blob_set_rawcontent_fromfile`
	- Rename `git_blob_writefile` -> `git_blob_create_fromfile`
	- Change `git_blob_create_fromfile`:
		The `path` argument is now relative to the repository's working dir
	- Add `git_blob_create_frombuffer`

commit.h
--------

	- Remove `git_commit_new`
	- Remove `git_commit_add_parent`
	- Remove `git_commit_set_message`
	- Remove `git_commit_set_committer`
	- Remove `git_commit_set_author`
	- Remove `git_commit_set_tree`

	- Add `git_commit_create`
	- Add `git_commit_create_v`
	- Add `git_commit_create_o`
	- Add `git_commit_create_ov`

tag.h
-----

	- Remove `git_tag_new`
	- Remove `git_tag_set_target`
	- Remove `git_tag_set_name`
	- Remove `git_tag_set_tagger`
	- Remove `git_tag_set_message`

	- Add `git_tag_create`
	- Add `git_tag_create_o`

tree.h
------

	- Change `git_tree_entry_2object`:
		New signature is `(git_object **object_out, git_repository *repo, git_tree_entry *entry)`

	- Remove `git_tree_new`
	- Remove `git_tree_add_entry`
	- Remove `git_tree_remove_entry_byindex`
	- Remove `git_tree_remove_entry_byname`
	- Remove `git_tree_clearentries`
	- Remove `git_tree_entry_set_id`
	- Remove `git_tree_entry_set_name`
	- Remove `git_tree_entry_set_attributes`

object.h
------------

	- Remove `git_object_new
	- Remove `git_object_write`

	- Change `git_object_close`:
		This method is now *mandatory*. Not closing an object causes a
		memory leak.

odb.h
-----

	- Remove type `git_rawobj`
	- Remove `git_rawobj_close`
	- Rename `git_rawobj_hash` -> `git_odb_hash`
	- Change `git_odb_hash`:
		New signature is `(git_oid *id, const void *data, size_t len, git_otype type)`

	- Add type `git_odb_object`
	- Add `git_odb_object_close`

	- Change `git_odb_read`:
		New signature is `(git_odb_object **out, git_odb *db, const git_oid *id)`
	- Change `git_odb_read_header`:
		New signature is `(size_t *len_p, git_otype *type_p, git_odb *db, const git_oid *id)`
	- Remove `git_odb_write`
	- Add `git_odb_open_wstream`
	- Add `git_odb_open_rstream`

odb_backend.h
-------------

	- Change type `git_odb_backend`:
		New internal signatures are as follows

			int (* read)(void **, size_t *, git_otype *, struct git_odb_backend *, const git_oid *)
			int (* read_header)(size_t *, git_otype *, struct git_odb_backend *, const git_oid *)
			int (* writestream)(struct git_odb_stream **, struct git_odb_backend *, size_t, git_otype)
			int (* readstream)( struct git_odb_stream **, struct git_odb_backend *, const git_oid *)

	- Add type `git_odb_stream`
	- Add enum `git_odb_streammode`

Signed-off-by: Vicent Marti <tanoku@gmail.com>

The "oid.h" header is now included instead of "object.h".

The old "revwalk.h" header has been removed; it was empty.

The `reset` call now removes the pushed commits so we can reuse
the revwalker. The API documentation has been updated with the details.

The method returns an int with the amount of objects free'd

One of my brainfarts made me export it as `git_repository_close` instead
of GC. Duh.

That way non-C bindings can use it.

The commit list was not being properly free'd when a walk was stopped
halfway through.

We now depend on libpthread on all Unix platforms (should be installed
by default) and use a simple wrapper for Windows threads under Win32.

Signed-off-by: Vicent Marti <tanoku@gmail.com>