Debugger: Relocate value_handlers.

- As they are currently only used by the VariablesView, move ValueHandler
  and related code into user_interface/gui.

src/apps/debugger/user_interface/gui/value/ValueHandler.cpp

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2009, Ingo Weinhold, [email protected].
+ * Copyright 2015, Rene Gollent, [email protected].
+ * Distributed under the terms of the MIT License.
+ */
+
+
+#include "ValueHandler.h"
+
+
+ValueHandler::~ValueHandler()
+{
+}
+
+
+status_t
+ValueHandler::CreateTableCellValueSettingsMenu(Value* value, Settings* settings,
+	SettingsMenu*& _menu)
+{
+	_menu = NULL;
+	return B_OK;
+}
+
+
+status_t
+ValueHandler::GetTableCellValueEditor(Value* value, Settings* settings,
+	TableCellValueEditor*& _editor)
+{
+	_editor = NULL;
+	return B_OK;
+}