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

git_merge_analysis will now return GIT_MERGE_CONFIG_NO_FASTFORWARD
when merge.ff=false and GIT_MERGE_CONFIG_FASTFORWARD_ONLY when
merge.ff=true

Fixed miscellaneous documentation errors.

We go through the different backends in order, so it's not an error if
at least one of the backends has the data we want.