Each leading tab is converted to two tabs, and any leading four spaces
is converted to one tab.  The intended tab size (for keeping most lines
within 80 columns) is now four.

This fixes https://savannah.gnu.org/bugs/?52755

.
Reported-by: Brand Huntsman <alpha@qzx.com>

When unindenting/uncommenting affected the bottom line of the marked
region, keep affecting this line also during subsequent consecutive
indenting/commenting.

This fixes https://savannah.gnu.org/bugs/?52718.

So that Commenting comes closer to the somewhat related Indenting
and Unindenting functions.

Also, make the descriptions for indenting/unindenting more precise.

So they will be found quicker.

Also fold two assignments into one.

They were mistakenly added by changeset fb85c055, four commits ago.

This fixes https://savannah.gnu.org/bugs/?52717.

Suggested-by: Brand Huntsman <alpha@qzx.com>

If the marked region ends at the start of a line, do not include that
line in the indenting/undenting or commenting/uncommenting.  This is
closer to what the eye would expect.

Unset the "Modified" marker only at the point where the file was last
saved -- if there is such a point, because it can be missing when the
undo stack was discarded.

This fixes https://savannah.gnu.org/bugs/?52689

.
Reported-by: Liu Hao <lh_mouse@126.com>
Original-idea-by: Brand Huntsman <alpha@qzx.com>

When doing that, there is no need to save and restore the Modified
state when writing a marked region.

This fixes https://savannah.gnu.org/bugs/?52651

.
Reported-by: David Lawrence Ramsey <pooka109@gmail.com>

The escape sequence "Esc [ Z" is a backtab on most supported terminals,
so make sure convert_sequence() treats it as such.

The function get_keycode() should never return zero -- it should
return either the code from ncurses or the given fallback code.

This fixes https://savannah.gnu.org/bugs/?52682.

To achieve that, fake the Shift key being held when indenting/
unindenting/commenting/uncommenting.
Reported-by: Brand Huntsman <alpha@qzx.com>

When the mark is on, instead of letting a <Tab> simply insert a Tab
character at the cursor position, let it indent the marked region.
Original-idea-by: Chris Allegretta <chrisa@asty.org>

Make both preceding character moves include the terminating byte.

The character move has already copied the terminating byte.
And a reallocation to save just one character of memory is
a waste of time.

And also allow it when lines are only partially indented.

This makes it possible to equalize the indentations of (accidentally)
unevenly indented lines: by first fully unindenting a group of lines,
and then reindenting them to the desired amount.
Suggested-by: Liu Hao <lh_mouse@126.com>

In this way we can delete things on the current line with ^K (after
Shift-selecting some text) without nano misdetecting a line change,

This fully fixes https://savannah.gnu.org/bugs/?52576.

Only when the cursor has moved off of the currrent line do we stop
prepending wrapped words to the next line.

This partially fixes https://savannah.gnu.org/bugs/?52576.

The option now causes nano to trim trailing whitespace also when
hardwrapping occurs while the user is typing.

This fulfills https://savannah.gnu.org/bugs/?52198.