added rendered_multi_polygon_, which works similar to rendered_polygon_ but is designed to store multiple sets of vertices in one vertex buffer. It stores the first_vertex_indices and vertex_counts, and then uses glMultiDrawArrays to render
added rendered_multi_polygon_, which works similar to rendered_polygon_ but is designed to store multiple sets of vertices in one vertex buffer. It stores the first_vertex_indices and vertex_counts, and then uses glMultiDrawArrays to render

mflagel/asdf_multiplat,mflagel/asdf_multiplat,mflagel/asdf_multiplat