Started work on string reordering. Just compiled, not yet tested.
src/bidi.c (bidi_paragraph_info): Delete unused struct.
(bidi_cache_idx, bidi_cache_last_idx): Declare EMACS_INT.
(bidi_cache_start): New variable.
(bidi_cache_reset): Reset bidi_cache_idx to bidi_cache_start, not
to zero.
(bidi_cache_fetch_state, bidi_cache_search)
(bidi_cache_find_level_change, bidi_cache_iterator_state)
(bidi_cache_find, bidi_peek_at_next_level)
(bidi_level_of_next_char, bidi_find_other_level_edge)
(bidi_move_to_visually_next): Compare cache index with
bidi_cache_start rather than with zero.
(bidi_fetch_char): Accept new argument STRING; all callers
changed. Support iteration over a string.
(bidi_paragraph_init, bidi_resolve_explicit_1)
(bidi_resolve_explicit, bidi_resolve_weak)
(bidi_level_of_next_char, bidi_move_to_visually_next): Support
iteration over a string.
(bidi_set_sor_type, bidi_resolve_explicit_1)
(bidi_resolve_explicit, bidi_type_of_next_char): ignore_bn_limit
can now be zero (for strings); special values 0 and -1 were
changed to -1 and -2, respectively.
(bidi_char_at_pos): New function.
(bidi_paragraph_init, bidi_resolve_explicit, bidi_resolve_weak):
Call it instead of FETCH_MULTIBYTE_CHAR.
(bidi_move_to_visually_next): Abort if charpos or bytepos were not
initialized to valid values.
(bidi_init_it): Don't initialize charpos and bytepos with invalid
values.
src/xdisp.c (compute_display_string_pos)
(compute_display_string_end): Accept additional argument STRING.
(init_iterator, reseat_1): Initialize bidi_it->string.s to NULL.
(reseat_to_string): Initialize bidi_it->string.s and
bidi_it->string.schars.
src/dispextern.h (struct bidi_string_data): New structure.
(struct bidi_it): New member `string'. Make flag members be 1-bit
fields, and put them last in the struct.
(compute_display_string_pos, compute_display_string_end): Update
prototypes.