To keep the blocks of text more-or-less aligned.

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.

Functions such as "io.close" should only be highlighted when the
package name ("io") is a word by itself, otherwise code such as
"fooio.close" gets unexpected partial highlighting.
Signed-off-by: Tom Levy <tomlevy93@gmail.com>

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.

Also, remove angle-bracketed "strings" -- they don't exist.

Also, remove the coloring of special single-quoted strings as they
get recolored by the subsequent general string-coloring command.

And remove the coloring of all-uppercase words, as other editors
do not color those either.

Either by whitespace or by the start of a line.

This avoids treating part of a URL as a comment.

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.