Made step to remove ASyncWindow in favour of usage of Future and FutureWatcher.

This should allow concurrency in the plugins to be independent from their container.

Contains also some work on the system for registering plugins.

pglab/plugin_support/PluginContentWidget.h

@@ -0,0 +1,33 @@
+#ifndef PGLPAGE_H
+#define PGLPAGE_H
+
+#include <QWidget>
+#include <vector>
+
+class IPluginContentWidgetContext;
+
+/// Provides a pluggable system for toolbar buttons and menu actions
+///
+/// We will need several kind of actions
+/// - create actions, these will create a new document or load from file , always available in menu
+/// - save actions available when on tab
+/// - edit actions
+/// - custom menu?
+///
+/// Can we use same groupings for toolbars and menu's
+/// How about additional toolbars?
+///
+class PluginContentWidget: public QWidget{
+public:
+	PluginContentWidget(IPluginContentWidgetContext *context, QWidget* parent = nullptr);
+	/// Returns the toolbar buttons for this page
+	virtual std::vector<QAction*> getToolbarActions();
+	virtual bool canClose();
+
+protected:
+	IPluginContentWidgetContext *context() { return m_context; }
+private:
+	IPluginContentWidgetContext *m_context;
+};
+
+#endif // PGLPAGE_H