Fix recorder crash due to use after free on user object.

The recorder used a ClientUser object pointer attached to the RecordBuffer
to be able to access a users session id and username . If the user joined
a server, made a noise and immediately left the server before the
RecordBuffer from the noise was processed the referenced ClientUser was
already deleted which crashed the client.

This fix retools RecordInfo and RecordBuffer to carry the information
previously needed from the ClientUser so that inside of the recorder
thread no dependencies to the ClientUser exist.
Refactoring of VoiceRecord.h/cpp according to new coding guidelines.