Tweaks to compiling APs for the going action.

§1. We will need three extra CPMCs (see Matching Action Patterns). 

enum NOWHERE_CPMC
enum SOMEWHERE_CPMC
enum NOT_NOWHERE_CPMC

int RTGoing::set_pattern_match_requirements(action_pattern *ap, int *cpm,
    int needed[MAX_CPM_CLAUSES], ap_clause *needed_apoc[MAX_CPM_CLAUSES]) {
    int cpm_count = *cpm;

    if (GoingPlugin::going_nowhere(ap)) {
        CPMC_NEEDED(NOWHERE_CPMC, NULL);
    } else if (GoingPlugin::going_somewhere(ap)) {
        CPMC_NEEDED(SOMEWHERE_CPMC, NULL);
    } else if (GoingPlugin::need_to_check_destination_exists(ap)) {
        CPMC_NEEDED(NOT_NOWHERE_CPMC, NULL);
    }

    *cpm = cpm_count;
    return FALSE;
}

§2. The implementation of these three clauses assumes throughout that variable number 1 in the shared variable set owned by the going action is the "to" variable, the one storing the room being gone to. 

int RTGoing::compile_pattern_match_clause(action_pattern *ap, int cpmc) {
    nonlocal_variable_emission nve =
        RTVariables::nve_from_mstack(GoingPlugin::id(), 1, TRUE);
    switch (cpmc) {
        case NOWHERE_CPMC:     Compile NOWHERE_CPMC test2.1;     return TRUE;
        case NOT_NOWHERE_CPMC: Compile NOT_NOWHERE_CPMC test2.2; return TRUE;
        case SOMEWHERE_CPMC:   Compile SOMEWHERE_CPMC test2.3;   return TRUE;
    }
    return FALSE;
}

§2.1. This handles the irregular usage "going nowhere". (The noun for "going" is ordinarily a direction.)

Compile NOWHERE_CPMC test2.1 = 

    EmitCode::inv(EQ_BIP);
    EmitCode::down();
        RTVariables::compile_NVE_as_val(NULL, &nve);
        EmitCode::val_number(0);
    EmitCode::up();

§2.2. The not-nowhere test is needed for patterns like "going from the Dining Room", which we want to match only where there is some destination: i.e., we don't want it to match an attempt to go in a direction not available in the map.

Compile NOT_NOWHERE_CPMC test2.2 = 

    EmitCode::inv(NE_BIP);
    EmitCode::down();
        RTVariables::compile_NVE_as_val(NULL, &nve);
        EmitCode::val_number(0);
    EmitCode::up();

§2.3. And this handles "going somewhere", testing that the destination is a room.

Compile SOMEWHERE_CPMC test2.3 = 

    parse_node *somewhere = Specifications::from_kind(K_room);
    RTActionPatterns::variable_matches_specification(
        TemporaryVariables::from_nve(nve, K_object),
        somewhere, K_object, FALSE);