Add Repository.Log() method (fix #298)

- CommitIter is now an interface
- The old CommitIter implementation is now called StorerCommitIter
- CommitWalker and CommitWalkerPost are now iterators (CommitPreIterator and CommitPostIterator).
- Remove Commit.History() method. There are so many ways to iterate a commit history, depending of the use case. Now, instead of use the History() method, you must use CommitPreIterator or CommitPostIterator.
- Move commitSorterer to references.go because is the only place that it is used, and it must not be used into another place.
- Make References method private, it must only be used into blame logic.
- Added a TODO into references method, where the sortCommits is used to remove it in a near future.

1 files changed, 2 insertions, 2 deletions

diff --git a/blame.go b/blame.go
index 2f0843d..99025fd 100644
--- a/blame.go
+++ b/blame.go
@@ -142,11 +142,11 @@ type blame struct {
 	graph [][]*object.Commit
 }
 
-// calculte the history of a file "path", starting from commit "from", sorted by commit date.
+// calculate the history of a file "path", starting from commit "from", sorted by commit date.
 func (b *blame) fillRevs() error {
 	var err error
 
-	b.revs, err = References(b.fRev, b.path)
+	b.revs, err = references(b.fRev, b.path)
 	if err != nil {
 		return err
 	}