Remove iOS arm64 target and validate project settings.
Merge pull request #340 from PiersonBro/remove-arm64-ios-target

Remove iOS arm64 target and validate project settings for Xcode 5.1
Keep a strong reference to the repository.

Under the covers, libgit2 could try to access the git_diff’s
repository, so we need to ensure that it stays alive as long as we are.
Merge pull request #341 from libgit2/fix-diff-repo

Give GTDiff a strong ref to its repository
Ignore xccheckout files.
Add a workspace for standalone development.
Pull dependencies from the workspace.
++libgit2
Merge pull request #343 from libgit2/update-libgit2

++libgit2
Note when to use the workspace.
Merge pull request #342 from libgit2/flatten-dependencies

Flatten dependencies