Objective C Second Alpha Drop

- Style fixups in the code.
- map<> serialization fixes and more tests.
- Autocreation of map<> fields (to match repeated fields).
- @@protoc_insertion_point(global_scope|imports).
- Fixup proto2 syntax extension support.
- Move all startup code to +initialize so it happen on class usage and not app startup.
- Have generated headers use forward declarations and move imports into generated code, reduces what is need at compile time to speed up compiled and avoid pointless rippling of rebuilds.
diff --git a/objectivec/Tests/unittest_objc.proto b/objectivec/Tests/unittest_objc.proto
index d288a30..3bb9276 100644
--- a/objectivec/Tests/unittest_objc.proto
+++ b/objectivec/Tests/unittest_objc.proto
@@ -44,6 +44,8 @@
   optional TestRecursiveMessageWithRepeatedField a = 1;
   repeated int32 i = 2;
   repeated string str = 3;
+  map<int32, int32> i_to_i = 4;
+  map<string, string> str_to_str = 5;
 }
 
 // Recursive message and extension to for testing autocreators at different