feat(reference): add ability to create direct reference

lib/src/bindings/reflog.dart

@@ -0,0 +1,56 @@
+import 'dart:ffi';
+import 'package:ffi/ffi.dart';
+import '../error.dart';
+import 'libgit2_bindings.dart';
+import '../util.dart';
+
+/// Read the reflog for the given reference.
+///
+/// If there is no reflog file for the given reference yet, an empty reflog
+/// object will be returned.
+///
+/// The reflog must be freed manually.
+///
+/// Throws a [LibGit2Error] if error occured.
+Pointer<git_reflog> read(Pointer<git_repository> repo, String name) {
+  final out = calloc<Pointer<git_reflog>>();
+  final nameC = name.toNativeUtf8().cast<Int8>();
+  final error = libgit2.git_reflog_read(out, repo, nameC);
+  calloc.free(nameC);
+
+  if (error < 0) {
+    throw LibGit2Error(libgit2.git_error_last());
+  } else {
+    return out.value;
+  }
+}
+
+/// Get the number of log entries in a reflog.
+int entryCount(Pointer<git_reflog> reflog) =>
+    libgit2.git_reflog_entrycount(reflog);
+
+/// Lookup an entry by its index.
+///
+/// Requesting the reflog entry with an index of 0 (zero) will return
+/// the most recently created entry.
+Pointer<git_reflog_entry> entryByIndex(Pointer<git_reflog> reflog, int idx) {
+  return libgit2.git_reflog_entry_byindex(reflog, idx);
+}
+
+/// Get the log message.
+String entryMessage(Pointer<git_reflog_entry> entry) {
+  final result = libgit2.git_reflog_entry_message(entry);
+  return result.cast<Utf8>().toDartString();
+}
+
+/// Get the committer of this entry.
+Map<String, String> entryCommiter(Pointer<git_reflog_entry> entry) {
+  final result = libgit2.git_reflog_entry_committer(entry);
+  var committer = <String, String>{};
+  committer['name'] = result.ref.name.cast<Utf8>().toDartString();
+  committer['email'] = result.ref.email.cast<Utf8>().toDartString();
+  return committer;
+}
+
+/// Free the reflog.
+void free(Pointer<git_reflog> reflog) => libgit2.git_reflog_free(reflog);