Show warning in Edit Table dialog when the grammar parser had trouble

The grammar parser returns a bool value to indicate if it encountered
some SQL feature that it doesn't understand yet. We might as well use
that bit of information and show it to the user.

src/EditTableDialog.cpp

@@ -29,9 +29,13 @@ EditTableDialog::EditTableDialog(DBBrowserDB* db, const QString& tableName, bool
     {
         // Existing table, so load and set the current layout
         QString sTablesql = pdb->getObjectByName(curTable).getsql();
-        m_table = sqlb::Table::parseSQL(sTablesql).first;
+        QPair<sqlb::Table, bool> parse_result = sqlb::Table::parseSQL(sTablesql);
+        m_table = parse_result.first;
+        ui->labelEditWarning->setVisible(!parse_result.second);
         ui->checkWithoutRowid->setChecked(m_table.isWithoutRowidTable());
         populateFields();
+    } else {
+        ui->labelEditWarning->setVisible(false);
     }
 
     // And create a savepoint

src/EditTableDialog.ui

@@ -288,6 +288,16 @@
      </layout>
     </widget>
    </item>
+   <item>
+    <widget class="QLabel" name="labelEditWarning">
+     <property name="text">
+      <string>&lt;html&gt;&lt;head/&gt;&lt;body&gt;&lt;p&gt;&lt;span style=&quot; font-weight:600; color:#ff0000;&quot;&gt;Warning: &lt;/span&gt;There is something with this table definition that our parser doesn't fully understand. Modifying and saving this table might result it in problems.&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
+     </property>
+     <property name="wordWrap">
+      <bool>true</bool>
+     </property>
+    </widget>
+   </item>
    <item>
     <widget class="QDialogButtonBox" name="buttonBox">
      <property name="orientation">