bug#9402: list-colors-display

[Juri Linkov]

Two problems related to `list-colors-display':

1. On a tty, running `M-x list-colors-display RET' displays
truncated hex color values like:              red    #cd000$
where $ is displayed at the end of the partial line.

To display the complete line this could be fixed by incrementing
`align-to' from 9 to 10 in `list-colors-print'.  But after that
when running it on X two extra spaces are displayed at the end
of these lines.

Maybe the bug is somewhere deeper in the display engine
that aligns differently on a tty and X?

2. New faces `gtk_selection_fg_color' and `gtk_selection_bg_color'
now are available for using on GTK but they are not listed in
`list-colors-display', and they can't be selected and completed in
`customize-face'.

There are more colors that are valid for using but hidden from users
such as e.g. on a tty: `unspecified-fg', `unspecified-bg'.