fixed up tlv serialisers:
 - Added RsTvlUnit: public RsTlvItem, which handles some of the infrstructure.
 - made TlvSize() SetTlv() and print() const.
 - split rstlvtypes into its bits and cleaned up header files.
 - added templated RsTlvList, imilar to cyrils id one.
 - removed GXS_GEN_TESTNET
 - cleanedup rsserviceids.