protocol_helper.hpp: Added field_type and field_bits

* These functions remove the need to use std::tuple_element to
  retrieve the underlyling field type and number of bits.
examples/test.cpp:  Test protocol::field_value and return failures

* Check that the first and last bit of each field value retrieved via
  protocol::field_value() is set to 1.
protocol_helper.hpp: Use field_bits and field_type
protocol_helper.hpp:  Fully qualify usage of protocol_helper classes