fixed #31: initialize target should be same name as declarations.

ProtocolBuffersMessage::decode will initialize properties with It's descriptor.
I've missed CamelCase string handle at this time.
fix #32 don't make full copy of parent message.

Child message will retain parent message object as for ProtocolBuffersMessage::containerOf method.
previous implementation made a full copy of parent message so it seems leak the memories.
fix testcase for 5.2
[added]
* added IDE friendly stub file.
* added ProtocolBuffersEnum::getName($value) method.

[bug fixes]
* #31 fixes potential for segmentation fault when using camel case field
* name.
* #32 don't waste memory when retain parent message.
prevent segmentation fault after throwing an exception.

object has been freed in some cases. this comit prevents that segv.
prevent segmentation fault when calling append method with message
accept repeated messages when calling setFrom or constructor #33