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, 8 insertions, 0 deletions

diff --git a/options.go b/options.go
index 1047d7e..d033654 100644
--- a/options.go
+++ b/options.go
@@ -177,3 +177,11 @@ type SubmoduleUpdateOptions struct {
 	// submodules (and so on). Until the SubmoduleRescursivity is reached.
 	RecurseSubmodules SubmoduleRescursivity
 }
+
+// LogOptions describes how a log action should be performed.
+type LogOptions struct {
+	// When the From option is set the log will only contain commits
+	// reachable from it. If this option is not set, HEAD will be used as
+	// the default From.
+	From plumbing.Hash
+}