Merge pull request #2170 from ethomson/clar

Update clar to e1990d6
corrected typo in error message
Merge pull request #2177 from shiftkey/typo-fix

corrected typo in error message
Add git_submodule_resolve_url()
Merge pull request #2175 from Yogu/submodule-resolve-url

Add git_submodule_resolve_url()
MSVC is silly
Fix pqueue sort boundary condition bug

If the pqueue comparison fn returned just 0 or 1 (think "a<b")
then the sort order of returned items could be wrong because there
was a "< 0" that really needed to be "<= 0".  Yikes!!!
Merge pull request #2184 from libgit2/rb/fix-revwalk-order-regression

Fix pqueue sort boundary condition bug
refs: fix copy-paste doc error
branch: constness fixes
repo: remove test which deletes HEAD

This is not something anybody would ever do; removing HEAD makes the
.git/ directory no longer be a repository, so we wouldn't be expected to
handle such a situation.
refs: append to the HEAD reflog when updating the current branch

When we update the current branch, we must also append to HEAD's reflog
to keep them in sync.

This is a bit of a hack, but as git.git says, it covers 100% of
default cases.
Add a few projects to the list
Merge pull request #2191 from libgit2/cmn/projects

Add a few projects to the list
Merge pull request #2190 from libgit2/cmn/current-branch-reflog

refs: append to the HEAD reflog when updating the current branch
Seamless support for NTLM/Kerberos auth on Windows
Merge pull request #2192 from phkelley/development

Seamless support for NTLM/Kerberos auth on Windows
Implement git_merge_base_octopus
Merge pull request #2189 from Aimeast/octopus

Implement git_merge_base_octopus
reflog: more comprehensive HEAD tests

The existing ones lack checking zeroed ids when switching back from an
unborn branch as well as what happens when detaching.

The reflog appending function mistakenly wrote zeros when dealing with a
detached HEAD. This explicitly checks for those situations and fixes
them.