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/control/card_editor.cpp

@@ -58,8 +58,8 @@ bool DataEditor::viewerIsCurrent(const ValueViewer* viewer) const {
 }
 
 
-void DataEditor::addAction(Action* action) {
-  set->actions.addAction(action);
+void DataEditor::addAction(unique_ptr<Action> action) {
+  set->actions.addAction(move(action));
 }
 
 // ----------------------------------------------------------------------------- : Selection

src/gui/control/card_editor.hpp

@@ -27,7 +27,7 @@ class DataEditor : public CardViewer {
   virtual DrawWhat drawWhat(const ValueViewer*) const;
   virtual bool viewerIsCurrent(const ValueViewer*) const;
   
-  virtual void addAction(Action* action);
+  virtual void addAction(unique_ptr<Action> action);
   inline SetP getSetForActions() { return set; }
   
   // --------------------------------------------------- : Selection

src/gui/control/card_list.cpp

@@ -179,7 +179,7 @@ bool CardListBase::doPaste() {
   ok = data.getCards(set, new_cards);
   if (!ok) return false;
   // add card to set
-  set->actions.addAction(new AddCardAction(ADD, *set, new_cards));
+  set->actions.addAction(make_unique<AddCardAction>(ADD, *set, new_cards));
   return true;
 }
 bool CardListBase::doDelete() {
@@ -188,7 +188,7 @@ bool CardListBase::doDelete() {
   getSelection(cards_to_delete);
   if (cards_to_delete.empty()) return false;
   // delete cards
-  set->actions.addAction(new AddCardAction(REMOVE, *set, cards_to_delete));
+  set->actions.addAction(make_unique<AddCardAction>(REMOVE, *set, cards_to_delete));
   return true;
 }
 
@@ -378,7 +378,7 @@ void CardListBase::onDrag(wxMouseEvent& ev) {
       findSelectedItemPos();
       if (item != selected_item_pos) {
         // move card in the set
-        set->actions.addAction(new ReorderCardsAction(*set, item, selected_item_pos));
+        set->actions.addAction(make_unique<ReorderCardsAction>(*set, item, selected_item_pos));
       }
       ev.Skip(false);
     }

src/gui/control/keyword_list.cpp

@@ -132,14 +132,14 @@ bool KeywordList::doPaste() {
   // add keyword to set
   KeywordP keyword = data.getKeyword(set);
   if (keyword) {
-    set->actions.addAction(new AddKeywordAction(ADD, *set, keyword));
+    set->actions.addAction(make_unique<AddKeywordAction>(ADD, *set, keyword));
     return true;
   } else {
     return false;
   }
 }
 bool KeywordList::doDelete() {
-  set->actions.addAction(new AddKeywordAction(REMOVE, *set, getKeyword()));
+  set->actions.addAction(make_unique<AddKeywordAction>(REMOVE, *set, getKeyword()));
   return true;
 }
 

src/gui/control/package_list.cpp

@@ -73,7 +73,7 @@ void PackageList::showData(const String& pattern) {
   FOR_EACH(p, matching) {
     // open image
     PROFILER(_("load package image"));
-    InputStreamP stream = p->openIconFile();
+    auto stream = p->openIconFile();
     Image img;
     Bitmap bmp;
     if (stream && image_load_file(img, *stream)) {