(CHARS_MODIFF, BUF_CHARS_MODIFF): New macros.
* buffer.c (Fbuffer_chars_modified_tick): New function returning
value of BUF_CHARS_MODIFF.
(syms_of_buffer): Defsubr it.
(Fget_buffer_create): Initialize BUF_CHARS_MODIFF.
* insdel.c (modify_region): New argument preserve_chars_modiff.
Set CHARS_MODIFF to MODIFF provided preserve_chars_modiff is zero.
(insert_1_both, insert_from_string_1, insert_from_buffer_1)
(adjust_after_replace, adjust_after_replace_noundo)
(replace_range, replace_range_2, del_range_2): Reset CHARS_MODIFF.
* lisp.h (modify_region): Add fourth argument in extern.
* casefiddle.c (casify_region): Call modify_region with fourth
argument zero to assert that CHARS_MODIFF is updated.
* editfns.c (Fsubst_char_in_region, Ftranslate_region_internal)
(Ftranspose_regions): Likewise.
* textprop.c (Fadd_text_properties, Fset_text_properties)
(Fremove_text_properties, Fremove_list_of_text_properties):
Call modify_region with fourth argument 1 to avoid that
CHARS_MODIFF is updated.
left_margin_width to left_margin_cols, right_margin_width to
right_margin_cols. All uses changed.
New members left_fringe_width, right_fringe_width,
fringes_outside_margins for per-buffer fringe settings.
New members scroll_bar_width and vertical_scroll_bar_type for
per-buffer scroll bar settings.
(PER_BUFFER_VAR_OFFSET): Renamed from BUFFER_LOCAL_VAR_OFFSET.
(PER_BUFFER_VAR_IDX): Renamed from BUFFER_LOCAL_VAR_IDX.
(PER_BUFFER_VALUE_P): Renamed from BUFFER_HAS_LOCAL_VALUE_P.
(SET_PER_BUFFER_VALUE_P): Renamed from SET_BUFFER_HAS_LOCAL_VALUE_P.
(PER_BUFFER_IDX): Renamed from BUFFER_LOCAL_IDX.
(PER_BUFFER_DEFAULT): Renamed from BUFFER_LOCAL_DEFAULT_VALUE.
(PER_BUFFER_VALUE): Renamed from BUFFER_LOCAL_VALUE.
(PER_BUFFER_SYMBOL): Renamed from BUFFER_LOCAL_SYMBOL.
(PER_BUFFER_TYPE): Renamed from BUFFER_LOCAL_TYPE.
(scroll_up_aggressively): New.
(scroll_down_aggressively): New.
(struct buffer): indicate_empty_lines renamed from
indicate_zv_lines.
(struct buffer): New member indicate_zv_lines.
(struct buffer): New members left_margin_width
and right_margin_width.
(struct buffer): Add member minibuffer_prompt_length
if PROMPT_IN_BUFFER.
