Propose unified rev-parse API
Implement unified git_revparse
Deprecate git_revparse_single and _rangelike
Add rev-list example to makefiles
commit: correctly detect the start of the commit message

The end of the header is signaled by to consecutive LFs and the commit
message starts immediately after. Jumping over LFs at the start of the
message is a bug and leads to creating different commits if
when rebuilding history.

This also fixes an empty commit message being returned as "\n".
Merge pull request #1467 from carlosmn/commit-parse

commit: correctly detect the start of the commit message
Fix compilation on OpenBSD
refdb tests: use the right variable size

Mixing int and size_t through pointers leads to problems
in big-endian machines.
Merge pull request #1468 from carlosmn/obsd-sparc64

OpenBSD & sparc64 fixes
Reintroduce git_revparse_single.
Redeploy git_revparse_single.
Change git_revparse to output git_object pointers

This will probably prevent many lookup/free
operations in calling code.
Clean up example code.
Clean up minor details
Merge remote-tracking branch 'ben/unified-revparse' into development
Allow git_remote_ls after disconnecting from the remote

Keep the data around until free, as expected by our own fetch example
Is this crazy?
git_revision -> git_revspec
Update docs
remote: don't try to update FETCH_HEAD if no extra heads exist

Don't try to update anything if there are no heads to update. This
saves us from trying to look into a fetch refspec when there is none.

A better fix for compatibility with git when using remotes without
refspecs is still needed, but this stops us from segfaulting.