Added ARB_map_buffer_range extension to the list.

OpenGL 3.0 specification is awesomely confused with extensions. The ones
listed in specs don't have the complete functionality and references
to related ARB extensions are nowhere to be found.

src/Context.cpp

@@ -75,8 +75,13 @@ const std::vector<Extension>& Extension::extensions(Version version) {
         _extension(GL,EXT,direct_state_access),
         _extension(GL,GREMEDY,string_marker)};
     static const std::vector<Extension> extensions300{
+        /**
+         * @todo Remove as it doesn't have all functionality present in GL 3.0
+         *      and leave only ARB_map_buffer_range?
+         */
         _extension(GL,APPLE,flush_buffer_range),
         _extension(GL,APPLE,vertex_array_object),
+        _extension(GL,ARB,map_buffer_range), // replaces APPLE_flush_buffer_range
         _extension(GL,ARB,color_buffer_float),
         _extension(GL,ARB,half_float_pixel),
         _extension(GL,ARB,texture_float),

src/Extensions.h

@@ -70,6 +70,7 @@ namespace GL {
         _extension(GL,ARB,draw_instanced,               GL210, GL310) // #44
         _extension(GL,ARB,geometry_shader4,             GL210, GL320) // #47
         _extension(GL,ARB,instanced_arrays,             GL210, GL330) // #49
+        _extension(GL,ARB,map_buffer_range,             GL210, GL300) // #50
         _extension(GL,ARB,texture_buffer_object,        GL210, GL310) // #51
         _extension(GL,ARB,texture_rg,                   GL210, GL300) // #53
         _extension(GL,ARB,uniform_buffer_object,        GL210, GL310) // #57