Adds a flag to protoc called --error_format which specifies what
convention to use when printing errors.  Default is GCC, but Microsoft
Visual Studio is another option.  This allows errors to be clickable in
the MSVS error log.

diff --git a/CHANGES.txt b/CHANGES.txt
index 2a86a63..94fe94e 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -9,6 +9,11 @@
     be normally except without a tag before each value (thus, they are
     tightly "packed").
 
+  protoc
+  * --error_format=msvs option causes errors to be printed in Visual Studio
+    format, which should allow them to be clicked on in the build log to go
+    directly to the error location. 
+
   C++
   * UnknownFieldSet now supports STL-like iteration.
   * Message interface has method ParseFromBoundedZeroCopyStream() which parses