Vselect_safe_coding_system_function): New variable.

Vselect_safe_coding_system_function): New variable.
(coding_category_table): This variable deleted.
(Vcoding_category_table): New variable.
(coding_category_name): Add "coding-category-iso-7-tight".
(detect_coding_iso2022): Check the mask
CODING_FLAG_ISO_DESIGNATION in CODING->FLAGS.  Check a new coding
category coding-category-iso-7-tight.
(DECODE_DESIGNATION): Decode only such designations that CODING
can handle.
(check_composing_code): New function.
(decode_coding_iso2022): Decode only such characters that CODING
can handle.
(encode_coding_iso2022): Before and after encoding composite
characters, reset designation and invocation status.
(detect_coding_sjis): Delete unnecessary check.
(detect_coding_big5): Likewise.
(encode_designation_at_bol): Check the validity of requested
designation register.
(setup_coding_system): Set requested designation registers for
non-supported charsets to
CODING_SPEC_ISO_NO_REQUESTED_DESIGNATION.  Set mask
CODING_FLAG_ISO_DESIGNATION in CODING->FLAGS.  Code tuned for
no-conversion and undecided.
(detect_coding): Adjusted for the new variable
Vcoding_category_table.
(syms_of_coding): Initialize Vcoding_category_table and staticpro
it.  Register select-safe-coding-system as a Lisp variable.

(DECODE_CHARACTER_ASCII): Update coding->produced_char;
(DECODE_CHARACTER_DIMENSION1): Likewise.
(Qraw_text, Qcoding_category): New variables.
(syms_of_coding): Intern and staticpro them.
(coding_system_table): New variable.
(CHARSET_OK, SHIFT_OUT_OK): New macros.
(detect_coding_iso2022): Detection algorithm improved.
(decode_coding_iso2022): Arg CONSUMED deleted, and the meaning of
return value changed.  Update members produced, produced_char,
consumed, consumed_char of the struct *coding.  Pay attention to
CODING_MODE_INHIBIT_INCONSISTENT_EOL.
(encode_coding_iso2022): Likewise.
(decode_coding_sjis_big5, encode_coding_sjis_big5): Likewise.
(decode_eol, encode_eol): Likewise.
(ENCODE_ISO_CHARACTER): Update coding->consumed_char.
(DECODE_SJIS_BIG5_CHARACTER): Update coding->produced_char.
(ENCODE_SJIS_BIG5_CHARACTER): Update coding->consumed_char.
(detect_coding(detect_coding(detect_ITIES and SKIP.
(detect_coding): Adjusted for the change of detect_coding_mask.
Update coding->heading_ascii.
(detect_eol_type): New arg SKIP.
(detect_eol): Adjusted for the change of detect_eol_type.
(ccl_codign_driver): New function.
(decode_coding): Arg CONSUMED deleted, and the meaning of return
value changed.  Update members produced, produced_char, consumed,
consumed_char of the struct *coding.
(encode_coding): Likewise.
(shrink_decoding_region, shrink_encoding_region): New function.
(code_convert_region, code_convert_string): Completely rewritten.
(detect_coding_sy(detect_coding_sy(detect_coding_sy(detect_coding_sy(detect_codiT.
(Fdetect_coding_string): New function.
(Fdecode_coding_region, Fencode_coding_region): Adjusted for the
change of code_convert_region.
(Fdecode_coding_string, Fencode_coding_string): Adjusted for the
change of code_convert_string.
(Fupdate_iso_coding_systems): New function.
(init_coding_once): Initialize coding_system_table.