Finally! The first complete and correct decode of an request for an
OpenSecureChannelService ;-)

M decodeInt16, decodeInt32: bugfix
M decodeExtensionObject: NO_BODY_IS_ENCODED =  no body
M encodeExtensionObject: same
M ExtensionObject_calcSize: same
M extensionObject_calcSize: same  (ups, strange...)
+ UA_ByteString_printx: dump character for character, nice for debugging
M UA_ExtensionObject: Length is already part of body, isn't it?
M SL_processMessage: some more debugging, added decoding of clientNonce
Merge branch 'master' of https://github.com/acplt/open62541