Temporarily disable colspan/rowspan generation

This is so we can merge the infrastuctural changes while we get on with
making the selection engine understand merged cells.

lib/importer/sheets.js

@@ -19,6 +19,11 @@ exports.GetHeader = (session) => {
 };
 
 function processMergedCells(wantedColumns, preview) {
+  // FIXME: Disable colspan/rowspan generation for now, until
+  // selectable_table.js is able to correctly handle selections across them.
+
+  return preview;
+
   // Pre-process colspan/rowspan attributes in cells, so the nunjucks macro
   // that makes an HTML table doesn't need to do clever things