QuestionnaireItemSVGQuality7pt: labels can now be defined via JS. (#7)

QuestionnaireItemQuality7pt: labels can now be defined via JS.
Fixes #4.

src/questionnaireitem_svg_quality7pt.js

@@ -1,5 +1,6 @@
 /**
 A QuestionnaireItem presenting the 7pt Quality scale as defined in ITU-T P.851 p. 19.
+Labels are by default in German - the content of the labels is defined in the SVG.
 
 @class QuestionnaireItemSVGQuality7pt
 @augments UIElement
@@ -10,16 +11,33 @@ A QuestionnaireItem presenting the 7pt Quality scale as defined in ITU-T P.851 p
 @param {string} [className] CSS class
 @param {string} question
 @param {boolean} [required=false]
+@param {string[]} [labels=["NOTE: Default labels are defined in the SVG."]] The labels (7 items; evaluated to string)
 */
-function QuestionnaireItemSVGQuality7pt(className, question, required) {
+function QuestionnaireItemSVGQuality7pt(className, question, required, labels) {
     QuestionnaireItemSVG.call(this, className, question, required);
+
+    this.labels = labels;
 }
 QuestionnaireItemSVGQuality7pt.prototype = Object.create(QuestionnaireItemSVG.prototype);
 QuestionnaireItemSVGQuality7pt.prototype.constructor = QuestionnaireItemSVGQuality7pt;
 QuestionnaireItemSVGQuality7pt.prototype._setupSVG = function() {
     this.scaleImage = document.createElementNS("http://www.w3.org/2000/svg", "svg");
     this.scaleImage.setAttribute("viewBox", "0 2 136.76 21.39");
     this.scaleImage.innerHTML = '@@include("../svg_scales/quality7pt_scale_include.svg")';
+
+    if (!(this.labels instanceof Array && this.labels.length === 7)) {
+        TheFragebogen.logger.warn(this.constructor.name + "._setupSVG()", "Exactly 7 labels are required as array. Got: " + this.labels);
+    } else {
+        TheFragebogen.logger.debug(this.constructor.name + "._setupSVG()", "Using custom labels: " + this.labels);
+
+        this.scaleImage.getElementById("label10").textContent = this.labels[0];
+        this.scaleImage.getElementById("label20").textContent = this.labels[1];
+        this.scaleImage.getElementById("label30").textContent = this.labels[2];
+        this.scaleImage.getElementById("label40").textContent = this.labels[3];
+        this.scaleImage.getElementById("label50").textContent = this.labels[4];
+        this.scaleImage.getElementById("label60").textContent = this.labels[5];
+        this.scaleImage.getElementById("label70").textContent = this.labels[6];
+    }
 };
 QuestionnaireItemSVGQuality7pt.prototype._getAnswerElements = function() {
     return this.scaleImage.getElementsByTagName("ellipse");