add branch iterator / remove useless repo from reference iterator
remove Branch struct, unify reference iterators
split out name iterator
various improvements to interface
remove channel based iteration for branch / ref. Add ReferenceNameIterator. All iterators use Next(). Remove interfaces.
Merge remote-tracking branch 'libgit/master' into branch-iterator
fix typo / return name iterator
Merge branch 'oid-parse-protection' into branch-iterator
merge with improved error handling logic
Merge pull request #66 from jezell/branch-iterator

Add branch iterator