message: Remove unused ReadVersion and WriteVersion
  CDataStream and CAutoFile had a ReadVersion and WriteVersion method
  that was never used. Remove them.
  backports bitcoin@50e8a9ccd78c8c20c3eac6618da7293078446b58
diff: @@ -208,8 +208,6 @@ public:
  int GetType() { return nType; }
  void SetVersion(int n) { nVersion = n; }
  int GetVersion() { return nVersion; }
  - void ReadVersion() { *this >> nVersion; }
  - void WriteVersion() { *this << nVersion; }
  CDataStream& read(char* pch, size_t nSize)
  {
  @@ -365,8 +363,6 @@ public:
  int GetType() { return nType; }
  void SetVersion(int n) { nVersion = n; }
  int GetVersion() { return nVersion; }
  - void ReadVersion() { *this >> nVersion; }
  - void WriteVersion() { *this << nVersion; }
  CAutoFile& read(char* pch, size_t nSize)
  {
  