documentation errors or imprecisions.

* Documented "text" import format.

before calling cucul_set_canvas_size(), otherwise it'll fill the new area
    with the current values.

int which shall be used as an UTF-32 character. We do not have any casting
    problems due to the signedness of chars because all characters were
    ASCII (ie. <= 0x7f) beforehands.

the canvas to 80 columns.

background.

a file and a memory area into a libcucul buffer.
  * Changed the cucul_import_canvas() prototype so that it uses libcucul
    buffers instead of simple memory areas.

sequences longer than 100 characters.
  * Documented the escape sequence format.

intermediate bytes.

in all .c files that needed it.

cucul_import_canvas().
  * Renamed cucul_create_export() into cucul_export_canvas() for consistency.