Remove coding: cookie and no-byte-compile flag.

Remove coding: cookie and no-byte-compile flag.
(IT-character-translations, cjk-codepages-alist): Remove variables.
(IT-display-table-setup, dos-cpNNN-setup): Remove functions.
(IT-unicode-translations): Remove charset and base elements.  Add translations
for Latin-1 characters.
(IT-setup-unicode-display): Accept a CODING argument.  Don't use base and
chset elements of IT-unicode-translations.  Don't wrap translation in "{...}".
Set up translations only for characters for which unencodable-char-position
returns non-nil.
(dos-codepage-setup): Don't use special-case codepages in cjk-codepages-alist.