(redisplay_text_width_charc_string): New function; delete

(redisplay_text_width_charc_string): New function; delete
`redisplay_text_width_emchar_string'.
(rtw_charc_dynarr): New variable; renamed from `rtw_emchar_dynarr'.
(redisplay_text_width_string): Use `rtw_charc_dynarr' instead of
`rtw_emchar_dynarr'; use `convert_bufbyte_string_into_charc_dynarr'
instead of `convert_bufbyte_string_into_emchar_dynarr'; use
`redisplay_text_width_charc_string' instead of
`redisplay_text_width_emchar_string'.
(redisplay_frame_text_width_string): Use `rtw_charc_dynarr' instead of
`rtw_emchar_dynarr'; use `convert_bufbyte_string_into_charc_dynarr'
instead of `convert_bufbyte_string_into_emchar_dynarr'.
(add_emchar_rune): Add <Charc> instead of <Emchar>; use
`redisplay_text_width_charc_string' instead of
`redisplay_text_width_emchar_string'.
(create_text_block): Modify for <struct rune> change.
(generate_formatted_string_db): Likewise.
(create_string_text_block): Likewise.
(pixel_to_glyph_translation): Likewise.