Create an abstract Manifest base class

This will help as we add support for another manifest type.

Signed-off-by: Shawn O. Pearce <sop@google.com>

manifest.py

@@ -0,0 +1,37 @@
+#
+# Copyright (C) 2009 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import os
+
+from editor import Editor
+from git_config import GitConfig
+from project import MetaProject
+
+class Manifest(object):
+  """any manifest format"""
+
+  def __init__(self, repodir):
+    self.repodir = os.path.abspath(repodir)
+    self.topdir = os.path.dirname(self.repodir)
+    self.globalConfig = GitConfig.ForUser()
+    Editor.globalConfig = self.globalConfig
+
+    self.repoProject = MetaProject(self, 'repo',
+      gitdir   = os.path.join(repodir, 'repo/.git'),
+      worktree = os.path.join(repodir, 'repo'))
+
+  @property
+  def IsMirror(self):
+    return self.manifestProject.config.GetBoolean('repo.mirror')