Made a step in removing knowledge of DatabaseWindow from QueryTab as an effort to move

in the direction of a plugin system.

DatabaseWindow now passes a Context to QueryTab and other pages that give those pages an
API for passing information up the system without knowing anything about the sytem.

pglab/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