global: implemented rudimentary memory manager to use available system memory

without forcing the OS to page swap

app/render/memorymanager.h

@@ -0,0 +1,33 @@
+#ifndef MEMORYMANAGER_H
+#define MEMORYMANAGER_H
+
+#include <QObject>
+
+class MemoryManager : public QObject
+{
+  Q_OBJECT
+public:
+  MemoryManager(QObject* parent = nullptr);
+
+  static void CreateInstance();
+  static MemoryManager* instance();
+  static void DestroyInstance();
+
+  static bool ShouldFreeMemory();
+
+public slots:
+  void ConsumedMemory();
+
+signals:
+  void FreeMemory();
+
+private:
+  static uint64_t GetAvailableMemory();
+
+  static MemoryManager* instance_;
+
+  static const uint64_t minimum_available_memory_;
+
+};
+
+#endif // MEMORYMANAGER_H