* pass const `char32_t` array and `QETermStyle` array to `ColorizeFunc`
* add `cp_colorize_line()` wrapper to call colorizer function on null
terminated buffer.
* remove unused `EditBuffer` colorize fields
* remove `EditState` field `colorize_func`: rely on `colorize_mode` only
* no longer combine style into codepoint buffer.
* remove `STYLE_BITS`, `STYLE_SHIFT`, `CHAR_MASK`
* rename `set_colorize_func` as `set_colorize_mode`
* rename `SET_COLOR` and `SET_COLOR1` as `SET_STYLE` and `SET_STYLE1`
* add documentation for buffer API functions
- char32_t is defined in cutils.h but may conflict with <uchar.h>
- all qe_isxxx functions take a char32_t
- add etf8x encoding for full range of char32_t type
- add utf8_decode_strict()
- add ustr_match_keyword()
- utf8_encode() / utf8_decode() handle up to 32 bits
- improve detect_charset():
- detect utf8 and utf8x
- avoid failure on partial utf8 sequence at end of buffer
- detect overlong utf8 sequences
- fix display bugs for code points beyond MAX_UNICODE_DISPLAY
- simplify do_compare_windows(), avoid magic char values.
- rename functions:
eb_encode_uchar -> eb_encode_char32
eb_insert_uchar -> eb_insert_char32
eb_insert_uchars -> eb_insert_char32_n
eb_match_uchar -> eb_match_char32
eb_delete_uchar -> eb_delete_char32
eb_replace_uchar -> eb_replace_char32
utf8_to_unicode -> utf8_to_char32
- use char32_t for all variables and arrays holding code-points
- fix some language syntax parsers.
- fix detect_eol_type_32bit(), used uint16_t instead of uint32_t
- bump VERSION to 5.4.0
