Revert "Add popdown* functions to top bar"

This reverts commit f985113.

Calling the `popdown*' functions causes the destructors of the views
to be called. As a result, the views lose their state.

Reverting this commit may use a little extra memory as the views are
kept in memory, but seems to have no other negative impact and
restores the behaviour known from 3.0.

Closes longturn#2329

client/top_bar.cpp

@@ -38,9 +38,7 @@
 #include "ratesdlg_g.h"
 #include "tileset/sprite.h"
 #include "top_bar.h"
-#include "views/view_economics.h"
 #include "views/view_map.h"
-#include "views/view_nations.h"
 #include "views/view_research.h"
 #include "views/view_units.h"
 
@@ -449,11 +447,7 @@ void top_bar::addWidget(QWidget *fsw)
  */
 void top_bar_show_map()
 {
-  popdown_units_view();
   popdown_city_dialog();
-  popdown_players_report();
-  popdown_economy_report();
-  popdown_science_report();
   queen()->game_tab_widget->setCurrentIndex(0);
 }