public int getLookupValueIdx(final int nameIdx, final String value) {
        final BExpressionLookupValue[] values = lookupValues.get(nameIdx);
        for (int i = 0; i < values.length; i++) {
            if (values[i].equals(value)) {
                return i;
            }
        }
        return -1;
    }
add a new lookup-value for the given name to the given lookupData array.
If no array is given (null value passed), the value is added to
the context-binded array. In that case, unknown names and values are
created dynamically.

@return a newly created value element, if any, to optionally add aliases
main/src/main/java/cgeo/geocaching/brouter/expressions/BExpressionContext.java