[apps] Less operations in willExitResponderChain if exiting app

If nextFirstResponder is nullptr, it means we are exiting the app, so
there is no need to relayout, reselect, ...
We did it bbefore because a long time ago, we used to keep all apps side
by side so they had to be thouroughly cleaned when exiting

apps/calculation/history_controller.cpp

@@ -46,6 +46,9 @@ void HistoryController::didBecomeFirstResponder() {
 }
 
 void HistoryController::willExitResponderChain(Responder * nextFirstResponder) {
+  if (nextFirstResponder == nullptr) {
+    return;
+  }
   if (nextFirstResponder == parentResponder()) {
     m_selectableTableView.deselectTable();
   }

apps/shared/float_parameter_controller.cpp

@@ -48,6 +48,9 @@ void FloatParameterController<T>::viewWillAppear() {
 
 template<typename T>
 void FloatParameterController<T>::willExitResponderChain(Responder * nextFirstResponder) {
+  if (nextFirstResponder == nullptr) {
+    return;
+  }
   if (parentResponder() == nullptr) {
     m_selectableTableView.deselectTable();
     m_selectableTableView.scrollToCell(0,0);

apps/shared/function_list_controller.cpp

@@ -207,6 +207,7 @@ void FunctionListController::didEnterResponderChain(Responder * previousFirstRes
 
 void FunctionListController::willExitResponderChain(Responder * nextFirstResponder) {
   if (nextFirstResponder == tabController()) {
+    assert(tabController() != nullptr);
     selectableTableView()->deselectTable();
     footer()->setSelectedButton(-1);
   }

apps/shared/interactive_curve_view_controller.cpp

@@ -165,7 +165,8 @@ void InteractiveCurveViewController::viewDidDisappear() {
 }
 
 void InteractiveCurveViewController::willExitResponderChain(Responder * nextFirstResponder) {
-  if (nextFirstResponder == nullptr || nextFirstResponder == tabController()) {
+  if (nextFirstResponder == tabController()) {
+    assert(tabController() != nullptr);
     curveView()->selectMainView(false);
     header()->setSelectedButton(-1);
     curveView()->reload();

apps/shared/tab_table_controller.cpp

@@ -17,6 +17,7 @@ void TabTableController::viewWillAppear() {
 
 void TabTableController::willExitResponderChain(Responder * nextFirstResponder) {
   if (nextFirstResponder == tabController()) {
+    assert(tabController() != nullptr);
     selectableTableView()->deselectTable();
     selectableTableView()->scrollToCell(0,0);
   }

apps/shared/values_controller.cpp

@@ -129,6 +129,7 @@ void ValuesController::didBecomeFirstResponder() {
 
 void ValuesController::willExitResponderChain(Responder * nextFirstResponder) {
   if (nextFirstResponder == tabController()) {
+    assert(tabController() != nullptr);
     selectableTableView()->deselectTable();
     selectableTableView()->scrollToCell(0,0);
     header()->setSelectedButton(-1);

apps/statistics/histogram_controller.cpp

@@ -70,7 +70,8 @@ void HistogramController::viewWillAppear() {
 }
 
 void HistogramController::willExitResponderChain(Responder * nextFirstResponder) {
-  if (nextFirstResponder == nullptr || nextFirstResponder == tabController()) {
+  if (nextFirstResponder == tabController()) {
+    assert(tabController() != nullptr);
     if (selectedSeriesIndex() >= 0) {
       m_view.dataViewAtIndex(selectedSeriesIndex())->setForceOkDisplay(false);
     }

apps/statistics/multiple_data_view_controller.cpp

@@ -79,7 +79,8 @@ void MultipleDataViewController::didEnterResponderChain(Responder * firstRespond
 }
 
 void MultipleDataViewController::willExitResponderChain(Responder * nextFirstResponder) {
-  if (nextFirstResponder == nullptr || nextFirstResponder == tabController()) {
+  if (nextFirstResponder == tabController()) {
+    assert(tabController() != nullptr);
     assert(*m_selectedSeriesIndex >= 0);
     multipleDataView()->deselectDataView(*m_selectedSeriesIndex);
     multipleDataView()->setDisplayBanner(false);

escher/src/selectable_table_view.cpp

@@ -58,7 +58,9 @@ void SelectableTableView::didEnterResponderChain(Responder * previousFirstRespon
 }
 
 void SelectableTableView::willExitResponderChain(Responder * nextFirstResponder) {
-  unhighlightSelectedCell();
+  if (nextFirstResponder != nullptr) {
+    unhighlightSelectedCell();
+  }
 }
 
 void SelectableTableView::deselectTable(bool withinTemporarySelection) {