Add a 'repo manifest' command whose help is the manifest file format

This should make it easier for users to discover the file format
on their own, and read about it.

Signed-off-by: Shawn O. Pearce <sop@google.com>
diff --git a/subcmds/manifest.py b/subcmds/manifest.py
new file mode 100644
index 0000000..69906fa
--- /dev/null
+++ b/subcmds/manifest.py
@@ -0,0 +1,44 @@
+#
+# 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
+import sys
+
+from command import Command
+
+class Manifest(Command):
+  common = False
+  helpSummary = "Manifest file"
+  helpUsage = """
+%prog
+"""
+  _helpDescription = """
+The repo manifest file describes the projects mapped into the client.
+"""
+
+  @property
+  def helpDescription(self):
+    help = self._helpDescription + '\n'
+    r = os.path.dirname(__file__)
+    r = os.path.dirname(r)
+    fd = open(os.path.join(r, 'docs', 'manifest-format.txt'))
+    for line in fd:
+      help += line
+    fd.close()
+    return help
+
+  def Execute(self, opt, args):
+    print >>sys.stderr, 'error: see repo help manifest'
+    sys.exit(1)