Add a find tool bar to the Browse Data tab

This adds a find tool bar to the Browse Data tab which allows the user
to search for values in the current table view. It only looks in
non-filtered rows and in non-hidden columns. It respected display
formats and sort order, too. The idea is to provide an additional level
of searching: the first one is done by using the filters and actually
reduces the number of rows in the view; the second level is done by
using the new find tool bar and allows you to look for values in the
remaining rows (or all rows if there is no filter).

See issue #1608.

src/TableBrowser.h

@@ -150,6 +150,9 @@ private slots:
     void browseDataSetTableEncoding(bool forAllTables = false);
     void browseDataSetDefaultTableEncoding();
 
+private:
+    void find(const QString& expr, bool forward, bool include_first = false);
+
 private:
     Ui::TableBrowser* ui;
     QIntValidator* gotoValidator;