Hardcoded "true" for use_extensions in fromProtoValue

[vrih]

All of the calls to fromProtoValue and getValAt in PersistentProtocolBufferMap have the use_extensions parameter hard coded to true. This causes runtime failures on schemas that don't use extensions.

To workaround for my specific schema I've had to build with line 393, line 713 and line 718 hardcoded to false. I assume there's a way to detect this but I'm not familiar enough with protobufs yet to implement.