Drop obsolete members after release v0.14
Normalize submodule paths on lookup

Fixes libgit2/libgit2#1845
Make probing work from within the packages folder

Fix #515

This aligns the package content to the deployment layout and thus
allows usage of the LibGit2Sharp assembly directly from within the
unpacked NuGet folder.
Update libgit2 binaries to 11f8336

https://github.com/libgit2/libgit2/compare/32e4992...11f8336
Clarified documentation of BranchTrackingDetails

The properties AheadBy, BehindBy and CommonAncestor are not only null if there is no tracking branch; they are also null if the tracking branch is empty (e.g. after cloning an empty repository)
Release LibGit2Sharp v0.14.1