zile: add support for basic color theming.

* lib/zile/bundle.lua: New file. Load a bundle from a file with
a "-bundle.lua" suffix to a Lua table using 'require'.
* lib/zile/default-color-bundle.lua: New file. Standard non-
olor terminal colors equivalent to before this changeset.
* lib/zemacs/main.lua (main): Load default colors.
* lib/zz/default-color-bundle.lua: New file. More colorful
defaults for Zz, including many settings which are not
implemented yet.
* lib/zz/main.lua (main): Load Zz default colors.
* lib/zile/term_redisplay (term_tidy, draw_line)
(draw_status_line): Use loaded colors instead of hard-coded
curses defaults.
* lib/zile/zile.mk (dist_pkgdata_DATA), lib/zz/zz.mk
(dist_zzdata_DATA): Add new files accordingly.
* lib/zile/term_curses (init_pair): Assign a bg/fg color pair
to a reusable pair id.
(term_get_attribute): Convert a bundle style and color table
into a curses attribute.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>