* indent.c: #include "region-cache.h".

* indent.c: #include "region-cache.h".
(character_width, disptab_matches_widthtab, recompute_width_table,
width_run_cache_on_off): New functions.
(compute_motion): Call width_run_cache_on_off.  If this buffer's
width run cache is enabled, consult it to see if we need to
traverse a region character-by-character; store information in the
cache after doing so.  Call find_before_next_newline instead of
writing out an equivalent loop explicitly, to take advantage of
the newline cache.
Doc fixes.