Clean up pointer use:

* Use unique_ptr for Actions instead of manual memory management
 * Use unique_ptr in KeywordDatabase
 * Use unique_ptr instead of shared_ptr for file formats
 * Don't pass shared_ptr to Reader/Writer, use references instead
Also
 * Switch to C++17 so we can use map::try_emplace

src/gui/set/cards_panel.cpp

@@ -325,7 +325,7 @@ void CardsPanel::onCommand(int id) {
       if (card_list->canSelectNext()) card_list->selectNext();
       break;
     case ID_CARD_ADD:
-      set->actions.addAction(new AddCardAction(*set));
+      set->actions.addAction(make_unique<AddCardAction>(*set));
       break;
     case ID_CARD_REMOVE:
       card_list->doDelete();

src/gui/set/keywords_panel.cpp

@@ -180,7 +180,7 @@ void KeywordsPanel::onCommand(int id) {
       list->selectNext();
       break;
     case ID_KEYWORD_ADD:
-      set->actions.addAction(new AddKeywordAction(*set));
+      set->actions.addAction(make_unique<AddKeywordAction>(*set));
       break;
     case ID_KEYWORD_REMOVE:
       if (list->canDelete()) {
@@ -370,7 +370,7 @@ void KeywordsPanel::onModeChange(wxCommandEvent& ev) {
   if (!list->getKeyword()) return;
   int sel = mode->GetSelection();
   if (sel >= 0 && (size_t)sel < set->game->keyword_modes.size()) {
-    set->actions.addAction(new ChangeKeywordModeAction(*list->getKeyword(), set->game->keyword_modes[sel]->name));
+    set->actions.addAction(make_unique<ChangeKeywordModeAction>(*list->getKeyword(), set->game->keyword_modes[sel]->name));
   }
 }
 

src/gui/set/random_pack_panel.cpp

@@ -528,7 +528,7 @@ void RandomPackPanel::onCommand(int id) {
     case ID_CUSTOM_PACK: {
       CustomPackDialog dlg(this, set, PackTypeP(), false);
       if (dlg.ShowModal() == wxID_OK) {
-        set->actions.addAction( new AddPackAction(ADD,*set,dlg.get()) );
+        set->actions.addAction(make_unique<AddPackAction>(ADD,*set,dlg.get()));
       }
       break;
     }
@@ -544,12 +544,12 @@ void RandomPackPanel::onPackTypeClick(wxCommandEvent& ev) {
           // update pack
           for (size_t i = 0 ; i < set->pack_types.size() ; ++i) {
             if (set->pack_types[i] == pick.pack) {
-              set->actions.addAction( new ChangePackAction(*set,i,dlg.get()) );
+              set->actions.addAction(make_unique<ChangePackAction>(*set,i,dlg.get()));
             }
           }
         } else {
           // delete pack
-          set->actions.addAction( new AddPackAction(REMOVE,*set,pick.pack) );
+          set->actions.addAction(make_unique<AddPackAction>(REMOVE,*set,pick.pack));
         }
       }
       break;

src/gui/set/stats_panel.cpp

@@ -238,7 +238,7 @@ void StatDimensionList::drawItem(DC& dc, int x, int y, size_t item) {
   StatsDimension& dim = *dimensions.at(item - show_empty);
   // draw icon
   if (!dim.icon_filename.empty() && !dim.icon.Ok()) {
-    InputStreamP file = game->openIn(dim.icon_filename);
+    auto file = game->openIn(dim.icon_filename);
     Image img(*file);
     if (img.HasMask()) img.InitAlpha(); // we can't handle masks
     Image resampled(21, 21);

src/gui/set/style_panel.cpp

@@ -171,18 +171,18 @@ void StylePanel::onStyleSelect(wxCommandEvent&) {
       // select no special style when selecting the same style as the set default
       stylesheet = StyleSheetP();
     }
-    set->actions.addAction(new ChangeCardStyleAction(card, stylesheet));
+    set->actions.addAction(make_unique<ChangeCardStyleAction>(card, stylesheet));
     Layout();
   }
 }
 
 void StylePanel::onUseForAll(wxCommandEvent&) {
-  set->actions.addAction(new ChangeSetStyleAction(*set, card));
+  set->actions.addAction(make_unique<ChangeSetStyleAction>(*set, card));
   Layout();
 }
 
 void StylePanel::onUseCustom(wxCommandEvent&) {
-  set->actions.addAction(new ChangeCardHasStylingAction(*set, card));
+  set->actions.addAction(make_unique<ChangeCardHasStylingAction>(*set, card));
 }
 
 BEGIN_EVENT_TABLE(StylePanel, wxPanel)