Win32 test fixes

Remote rename fixes

Update AUTHORS

Add me. :)

Tighten up which references we consider for renaming so we don't try to
rename unrelated ones and end up with unexplained references.

If there is a reference on the target namespace, git overwrites it, so
let's do the same.

When there is a reference in the target namespace, we should overwrite
it. Instead it gets a different name under the current code.

clone: re-use the local transport's path resolution

Concurrent ref iterator access

Whe already worked out the kinks with the function used in the local
transport. Expose it and make use of it in the local clone method
instead of trying to work it out again.

Remote: Set an error when a remote cannot be found.

Documentation formatting fixes

The documentation has shown this as a single enum for a long time. These
should in fact be two enums. One with the bits for the flags and another
with the bits for the extended flags.

These are some issues I found while playing around with the new parser
for docurium.

This lets us work without worrying about what's happening but work on a
snapshot.

If we remove a reference while we're iterating through the packed refs,
the position in the iterator will be off.

remote: build up the list of refs to remove

When removing the remote-tracking branches, build up the list and remove
in two steps, working around an issue with the iterator. Removing while
we're iterating over the refs can cause us to miss references.

Minor fixes to binary diff code

Inside `git_remote_load`, the calls to `get_optional_config` use
`giterr_clear` to unset any errors that are set due to missing config
keys. If neither a fetch nor a push url config was found for a remote,
we should set an error again.

Ignore core.safecrlf=warn until we have a warn infrastructure

Respect core.precomposeunicode = true in more cases.

This adds another assertion to ensure that the reference name inside
the git_reference struct returned by `git_branch_create` is returned as
precomposed if `core.precomposeunicode` is enabled.

This tests that decomposed branch names are correctly precomposed when
passed to `git_branch_move` and `core.precomposeunicode` is enabled.

This fixes two issues I found when core.precomposeunicode is enabled:

* When creating a reference with a NFD string, the returned
  git_reference would return this NFD string as the reference’s
  name. But when looking up the reference later, the name would
  then be returned as NFC string.
* Renaming a reference would not honor the core.precomposeunicode and
  apply no normalization to the new reference name.

The error would be uninitialized if we take a snapshot of a config with
no backends.

Add support for --author flag in example log implementation

Local clone

Assert the exact amount of links we expect. While there, check that a
plain git_clone() automatically chooses to link.

[Blob] Update documentation for is_binary.

filter.h tells me that we check the first 8000 bytes.

If requested, git_clone_local_into() will try to link the object files
instead of copying them.

This only works on non-Windows (since it doesn't have this) when both
are on the same filesystem (which are unix semantics).