View2D had some inconsistencies making it error prone in some cases. - Inconstant checking for NULL x/y args. Disallow NULL args for x/y destination pointers, instead add: - UI_view2d_region_to_view_x/y - UI_view2d_view_to_region_x/y - '_no_clip' suffix wasn't always used for non-clipping conversion, switch it around and use a '_clip' suffix for all funcs that clip. - UI_view2d_text_cache_add now clips before adding cache. - '_clip' funcs return a bool to quickly check if its in the view. - add conversion for rectangles, since this is a common task: - UI_view2d_view_to_region_rcti - UI_view2d_region_to_view_rctf