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.

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).

When passed the LINK_FILES flag, the recursive copy will hardlink files
instead of copying them.

A call like git_clone("./foo", "./foo1") writes origin's url as './foo',
which makes it unusable, as they're relative to different things.

Go with git's behaviour and store the realpath as the url.

When git is given such a path, it will perform a "local clone",
bypassing the git-aware protocol and simply copying over all objects
that exist in the source.

Copy this behaviour when given a local path.

index: check for valid filemodes on add

travis: build on osx too

Fixed permissions on template directories.

Fix compile error on Visual Studio

Introduce GIT_MERGE_CONFIG_* for merge.ff settings