This commit removes the member function
void SummaryState::update(const ecl::smspec_node&, double)
and places an equivalent implementation into Summary.cpp's private
helper function namespace. Doing so allows us to make the summary
state object independent of the 'libecl' library.
- Change SummaryState::add() -> SummaryState::update(), the
SummaryState::update() method is semantically aware of totals.
- Add an internal variable to the SummaryState class to keep track of the
elapsed simulation time.
