PENDING changes

## from changes-20210321-20210406.txt
- all tabbed & tab widget functions

## from changes-20210406-20210410.txt
missing methods:
- [ ] ncdirect_stream

## from changes-20120518-20210603.txt

missing methods:
- [ ] nccell_width
- [ ] ncdirect_styles (method)
- [ ] ncdirect_supported_styles (method)
- [ ] ncplane_erase_region
- [ ] notcurses_cursor_yx

## from changes-20210603-20210704.txt …

missing imports & methods:
- [ ] ncpile_render_to_buffer
- [ ] ncpile_render_to_file
- [ ] nccells_ascii_box
- [ ] nccells_heavy_box
- [ ] nccells_light_box