public List<VariableEntry> getEntries() {
        final List<VariableEntry> rows = new ArrayList<>();
        for (String v : this.variableList) {
            if (this.variableMap.get(v) == null) {
                continue;
            }
            rows.add(new VariableEntry(
                    this.variablesSet.get(v) == null ? -1 : Objects.requireNonNull(this.variablesSet.get(v)),
                    v, Objects.requireNonNull(this.variableMap.get(v)).getFormulaString()));
        }
        return rows;
    }
Tidies up this variable list. This means doing the following things:
* remove empty entries without dependency of any other var (or from varsToKeep list)
* add empty entries for all missing vars
* sorts vars alphabetically
main/src/main/java/cgeo/geocaching/utils/formulas/VariableList.java