- Update to version 1.7.2
* Exported `ncvisual_default_blitter()`, so that the effective
value of `NCBLIT_DEFAULT` can be determined.
* Added `NCREADER_OPTION_CURSOR`, instructing the `ncreader` to
make the terminal cursor visible, and manage the cursor's
placement.

- Update to version 1.7.1
* Renamed `CELL_SIMPLE_INITIALIZER` to `CELL_CHAR_INITIALIZER`,
and `cell_load_simple()` to `cell_load_char()`.
* Renamed `ncplane_putsimple()` to `ncplane_putchar()`,
`ncplane_putsimple_stainable()` to `ncplane_putchar_stainable()`,
and `ncplane_putsimple_yx()` to `ncplane_putchar_yx()`.

- Run unittest

- Update to version 1.7.0
* Added `notcurses_ucs32_to_utf8()` conversion helper.
* `ncdirect_init()` now takes a third `uint64_t flags` parameter.
No flags have been defined, and this parameter ought be set
to 0.

- Update to version 1.6.20
* Added convenience functions `ncplane_y()` and `ncplane_x()`,
components of longstanding `ncplane_yx()`.
* `ncreel` functions now generally call `ncreel_redraw()`
themselves. This includes `ncreel_add()`, `ncreel_del()`,
`ncreel_next()`, and `ncreel_prev()`. `ncreel_redraw()` need
only be called to update tablets.
* In order to conform with CMake naming conventions, our CMake