opengl 3.3 renderer integration, minor renderer tweaks

uiwidgets.h

@@ -0,0 +1,17 @@
+/*
+This Source Code Form is subject to the
+terms of the Mozilla Public License, v.
+2.0. If a copy of the MPL was not
+distributed with this file, You can
+obtain one at
+http://mozilla.org/MPL/2.0/.
+*/
+
+#pragma once
+
+namespace ImGui {
+
+bool BufferingBar( const char* label, float value, const ImVec2& size_arg, const ImU32& bg_col, const ImU32& fg_col );
+bool Spinner( const char* label, float radius, int thickness, const ImU32& color );
+
+} // namespace ImGui