This added a flag to the `git_repository_set_workdir()` function
that enables generation of a `.git` gitlink file that links the
new workdir to the parent repository.  Essentially, the flag tells
the function to write out the changes to disk to permanently set
the workdir of the repository to the new path.

If you pass this flag as true, then setting the workdir to something
other than the default workdir (i.e. the parent of the .git repo
directory), will create a plain file named ".git" with the standard
gitlink contents "gitdir: <repo-path>", and also update the
"core.worktree" and "core.bare" config values.

Setting the workdir to the default repo workdir will clear the
core.worktree flag (but still permanently set core.bare to false).

BTW, the libgit2 API does not currently provide a function for
clearing the workdir and converting a non-bare repo into a bare one.

Adding a new config iteration function that let's you iterate
over just the config entries that match a particular regular
expression.  The old foreach becomes a simple use of this with
an empty pattern.

This also fixes an apparent bug in the existing `git_config_foreach`
where returning a non-zero value from the iteration callback was
not correctly aborting the iteration and the returned value was
not being propogated back to the caller of foreach.

Added to tests to cover all these changes.

Adding 0x85 to `git__isspace` since we also look for that in filter.c
as a whitespace character.

This makes it easy to take a buffer containing a path with relative
references (i.e. .. or . path segments) and resolve all of those
into a clean path.  This can be applied to URLs as well as file
paths which can be useful.

As part of this, I made the drive-letter detection apply on all
platforms, not just windows.  If you give a path that looks like
"c:/..." on any platform, it seems like we might as well detect
that as a rooted path.  I suppose if you create a directory named
"x:" on another platform and want to use that as the beginning
of a relative path under the root directory of your repo, this
could cause a problem, but then it seems like you're asking for
trouble.

* `git_buf_rfind` (with tests and tests for `git_buf_rfind_next`)
* `git_buf_puts_escaped` and `git_buf_puts_escaped_regex` (with tests)
  to copy strings into a buffer while injecting an escape sequence
  (e.g. '\') in front of particular characters.

examples: add README

Bring back `entry_bypath`

diff: make inter-hunk-context default value git-compliant

Point to the libgit2-glib wiki page

Fix libgit2 on GNU/Hurd.

On GNU, the d_name field of the dirent structure is defined as "char d_name[1]",
so we must allocate more than sizeof(struct dirent) bytes, just like on Sun.

revparse: fix parsing of date specifiers

Replace incorrect 'it' with 'if' in documentation

Default in git core is 0, not 3

More git_revparse_single ENOTFOUND use cases

It causes the clar testsuite to abort on Windows, and isn't necessary.

Smaller, simpler, faster.

Small revparse colon syntax improvements

Once a file is registered, there is no way to deregister it, even
after the structure that contains it is no longer needed and has been
freed. This may be the source of #624.

Allow and use the deregister function to remove our file from the
global list.

indexer: don't use '/objects/pack/' unconditionally

Not everyone who indexes a packfile wants to put it in the standard
git repository location.

Repo reinit fix + enhanced test coverage

Topic/refs fromglob

indexer: start parsing input data immediately