Add the ASS sub document and the ASS tree

Also add views for the ASS tree in read only mode for now

src/UI/DocumentViews/AssLinesModel.cc

@@ -68,25 +68,9 @@ AssLinesModel::data(const QModelIndex &index, int role) const noexcept
     const Item *line         = static_cast<const Item *>(index.internalPointer());
     const Item::Field column = static_cast<Item::Field>(index.column());
 
-    // Check state only for the IsComment
-    if (role == Qt::CheckStateRole && column == Item::Field::IsComment) {
-        return line->getIsComment() ? Qt::Checked : Qt::Unchecked;
-    }
-
-    // Is comment is centered
-    else if (role == Qt::TextAlignmentRole && column == Item::Field::IsComment) {
-        return Qt::AlignCenter;
-    }
-
     // Display role
-    else if (Qt::DisplayRole == role) {
+    if (Qt::DisplayRole == role) {
         switch (column) {
-        case Item::Field::Style:
-            return line->getLineStyle();
-
-        case Item::Field::IsComment:
-            return QVariant();
-
         case Item::Field::Text:
             return line->getLineText();