Add line blame (#116)

* Add line blame

Signed-off-by: Jonas Franz <info@jonasfranz.software>

* Use uint instead of int to prevent failures

Signed-off-by: Jonas Franz <info@jonasfranz.software>

repo_blame.go

@@ -4,7 +4,21 @@
 
 package git
 
+import "fmt"
+
 // FileBlame return the Blame object of file
 func (repo *Repository) FileBlame(revision, path, file string) ([]byte, error) {
 	return NewCommand("blame", "--root", file).RunInDirBytes(path)
 }
+
+// LineBlame returns the latest commit at the given line
+func (repo *Repository) LineBlame(revision, path, file string, line uint) (*Commit, error) {
+	res, err := NewCommand("blame", fmt.Sprintf("-L %d,%d", line, line), "-p", revision, file).RunInDir(path)
+	if err != nil {
+		return nil, err
+	}
+	if len(res) < 40 {
+		return nil, fmt.Errorf("invalid result of blame: %s", res)
+	}
+	return repo.GetCommit(string(res[:40]))
+}