louvain as hard-coded default for fillAttrsInForm

it becomes the default even if not selected in defaultColoring (because it is always available and interesting) and its filled with correct values even if never run before and therefore not in TW.Facets list

explorerjs.html

@@ -662,7 +662,6 @@
                        <label for="choose-attr" class="smlabel input-group-addon">Attribute</label>
                        <select id="choose-attr" name="choose-attr"
                                class="custom-select form-control">
-                               <option selected value="0"></option>
                                <!-- filled by fillAttrsInForm(.) -->
                        </select>
                      </div>

twmain/extras_explorerjs.js

@@ -1009,7 +1009,7 @@ function fillAttrsInForm(menuId, optionalAttTypeConstraint) {
   }
 
   // 2- ls | uniq all options (no matter what active type they belong too)
-  let uniqOptions = {}
+  let uniqOptions = {'clust_louvain': true}
   for (let tid in actypes) {
     let ty = actypes[tid]
     for (var att in TW.Facets[ty]) {
@@ -1035,6 +1035,9 @@ function fillAttrsInForm(menuId, optionalAttTypeConstraint) {
     else {
       opt.innerText = "(" + att + ")"
     }
+    if (att == 'clust_louvain') {
+      opt.selected = true
+    }
     if (att in TW.sigmaAttributes) {
       opt.dataset.opttype = "auto"
     }
@@ -1043,6 +1046,8 @@ function fillAttrsInForm(menuId, optionalAttTypeConstraint) {
     }
     elChooser.appendChild(opt)
   }
+
+  showAttrConf(null, 'clust_louvain')
 }
 
 // for optional questions:
@@ -1088,8 +1093,8 @@ function colChangedHandler() {
 }
 
 
-function showAttrConf() {
-  let attrTitle = this.value
+function showAttrConf(event, optionalAttrname) {
+  let attrTitle = optionalAttrname || this.value
   let settings = TW.facetOptions[attrTitle] || {}
   document.getElementById('attr-translation').value = settings.legend || attrTitle
   document.getElementById('attr-col').value = settings.col || 'gradient'