This is a running list of things to fix / add to the library

* Hicolor palette mapping mode

* Replace parts of color_map.c code with ncurses equivlents:
  * alloc_pair()
  * find_pair()
  * free_pair()

* Utilize NCURSES_NO_UTF8_ACS instead of similar in vterm_utf8.c

* Use ncurses extensions for more colors and pairs when avaialble

