(chise-tex-coded-charset-expression-alist): Add setting for

(chise-tex-coded-charset-expression-alist): Add setting for
`=adobe-japan1-5'.
(chise-tex-accents-macro-alist): Add setting for <COMBINING HORN>.
(chise-tex-encode-ucs-char-at-point):
- Encode <LATIN SMALL LETTER DOTLESS I> as "\i{}".
- Use "\LATINeng{}" to encode <LATIN SMALL LETTER ENG>.
- Encode <LATIN SMALL LETTER ALPHA> as "\textscripta{}".
- Encode <LATIN SMALL LETTER OPEN E> as "\IPAepsilon{}".
- Encode <LATIN SMALL LETTER IOTA> as "\IPAiota{}".
- Encode <LATIN SMALL LETTER REVERSED R WITH FISHHOOK> as
  "\IPArevfishhookr{}".
- Encode <MODIFIER LETTER LEFT HALF RING> as \textrevapostrophe{}.
- Encode <SUPERSCRIPT FOUR> as "$^4$".
(chise-tex-encode-region-for-utf-8-jis):
- Don't encode <LATIN SMALL LETTER S WITH ACUTE>.
- Encode <LATIN SMALL LIGATURE OE> as "\oe{}".
- Encode SIP characters as "\UCSsip{XXXXX}".