Trash instances instead of deleting (when possible) (#549)

Squashed because of :pofat: commit history

launcher/InstanceList.h

@@ -19,6 +19,8 @@
 #include <QAbstractListModel>
 #include <QSet>
 #include <QList>
+#include <QStack>
+#include <QPair>
 
 #include "BaseInstance.h"
 
@@ -46,6 +48,12 @@ enum class GroupsState
     Dirty
 };
 
+struct TrashHistoryItem {
+    QString id;
+    QString polyPath;
+    QString trashPath;
+    QString groupName;
+};
 
 class InstanceList : public QAbstractListModel
 {
@@ -102,6 +110,9 @@ public:
     void setInstanceGroup(const InstanceId & id, const GroupId& name);
 
     void deleteGroup(const GroupId & name);
+    bool trashInstance(const InstanceId &id);
+    bool trashedSomething();
+    void undoTrashInstance();
     void deleteInstance(const InstanceId & id);
 
     // Wrap an instance creation task in some more task machinery and make it ready to be used
@@ -180,4 +191,6 @@ private:
     QSet<InstanceId> instanceSet;
     bool m_groupsLoaded = false;
     bool m_instancesProbed = false;
+
+    QStack<TrashHistoryItem> m_trashHistory;
 };