Started working on implementing UBA v6.3.
Modified struct bidi_it as required by UBA changes.
Introduced BIDI_MAXDEPTH instead of BIDI_MAXLEVEL; users changed.
Added bidi_fetch_char_skip_isolates.
Changed bidi_paragraph_init to use bidi_fetch_char_skip_isolates.
Removed uses of bidi_ignore_explicit_marks_for_paragraph_level.
Reverted temporary kludges that treat isolate initiators as weak characters.
Remove bidi_ignore_explicit_marks_for_paragraph_level.
Finished coding of explicit directional format characters.

Refactored part of bidi_paragraph_init into find_first_strong_char.
Removed old kludges from bidi_it and the code.
sor is now sos.
Fix find_first_strong_char and implement Unicode 8.0 isolate corrections.

find_first_strong_char accepts 1 additional argument, which says to stop
at the PDI that matches the FSI where we started; callers changed.
Implemented suggested Unicode 8.0 corrections for type of RLI/LRI/PDI.
Updated pushing and popping the bidi stack, and sos calculations.
Added the necessary members to bidi_stack.
Updated bidi_resolve_weak.  Removed next_en_* members from stack.
Fixed problems revealed by -Wall.
Added BidiBrackets.txt and related Unicode properties to unidqata-gen.el.
Optimize memory footprint of the bidi level stack.
Added initial version of biditest.el and Unicode data file it needs.
Added bidi-resolved-levels, with a bug.
Use the level stack for initial level below bidi_level_of_next_char.

This still crashes in TUTORIAL.he.
Fix assertion violations due to a bug in bidi_set_sos_type; add assertions.
Rewrite LRI/RLI/FSI handling in bidi_resolve_explicit_1.
Fixed bidi_resolve_explicit_1 wrt isolate initiators and PDF.

bidi_resolve_neutral needs to be fixed, as it now aborts at line 2432.
Adapt bidi_resolve_neutral to new treatment of PDF to avoid assertion violations.
Remove the ignore_bn_limit ``optimization''.
Fix bidi_resolve_explicit when one directional control follows another.
Fix N1 and N2.  Remove special level for PDF.
Improve glyphless glyph display in .gdbinit/pgx.
Finished writing code for isolates and fixed a few bugs (no parens yet).