Resolve "Simplification du code (jalhyd#58)"

Closes #104 (closed)

src/app/formulaire/ngparam.ts

-import { ParamDefinition, Pair, ParamDomain, ParamValueMode, INumberIterator, Nub, Observer, asObservable } from "jalhyd";
+import { Interval, ParamDefinition, ParamDomain, ParamValueMode, INumberIterator, Nub, Observer, asObservable } from "jalhyd";
 
 import { InputField } from "./input-field";
 import { Dependency } from "./dependency/dependency";
@@ -6,7 +6,6 @@ import { DependencyConditionType } from "./dependency/dependency-condition";
 import { ValueDependencyCondition } from "./dependency/value-dependency-condition";
 import { ServiceFactory } from "../services/service-factory";
 import { ApplicationSetupService } from "../services/app-setup/app-setup.service";
-import { StringMap } from "../stringmap";
 import { FormulaireNode } from "./formulaire-node";
 
 export enum ParamRadioConfig {
@@ -121,7 +120,7 @@ export class NgParameter extends InputField implements Observer {
         this._paramValues.max = v;
     }
 
-    public get stepRefValue(): Pair {
+    public get stepRefValue(): Interval {
         return this._paramValues.stepRefValue;
     }