When the user wants to get a backtrace, the crash handler shouldn't
kick in.

Upon a segmentation fault or an abort signal, instead of crashing,
losing all changes, and leaving the terminal in curses mode, nano
now calls die(), to save any changed buffers and to restore the
terminal to a usable state.

For the remote chance that nano segfaults in die(), the handler for
SIGSEGV and for SIGABRT is reset to its default value as soon as the
signal fires, to prevent a crash-handler loop.

Since a core dump is usually more helpful for debugging, the crash
handler is not included in a debug build.

This addresses https://savannah.gnu.org/patch/?9623

.
Signed-off-by: Devin Hussey <husseydevin@gmail.com>

Also, add a period after the "Read nn lines" message, and
don't let the next shell prompt overwrite this message.

This addresses https://savannah.gnu.org/bugs/?53779.

This addresses https://savannah.gnu.org/bugs/?53777.

Don't try to re-enter curses mode when the terminal is not in
the correct state yet.

This fixes https://savannah.gnu.org/bugs/?53720.

Also, reshuffle a condition so it takes up less space.

This will make the tiny version slightly smaller.

In the preceding commit, open_buffer() was changed so that it gets
told whether to load into a new buffer or not, so it is no longer
needed to convey this information through a flag.

And also prevent a theoretical crash for restricted prompt functions.

This fixes a regression introduced by commit 54103d8e: a crash that
can be triggered by running 'nano --restrict' and pressing <Insert>.

This addresses https://bugzilla.redhat.com/1558532.

Signed-off-by: Liu Hao <lh_mouse@126.com>

This avoids a bunch of warnings when compiled with -pedantic:

	ISO C forbids comparison of ‘void *’ with function pointer

As, since commit 0e30177d, the scrollup and scrolldown commands
no longer intend to move the cursor, they should not be seen as
movement functions.

Also, it is not guaranteed that functions are ordered in the same
way in the binary as in the source code, so an ordered comparison
of function pointers will not always work.

This fixes https://savannah.gnu.org/bugs/?53333.

This fixes https://savannah.gnu.org/bugs/?53317

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

This assumes that all movement functions are located together,
starting with to_first_line() and ending with do_right().

This fixes https://savannah.gnu.org/bugs/?53195

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

The implant() function itself cannot be bound to anything, so it
is not in the linked list of functions -- trying to find it would
lead to a NULL pointer, and thus to a segfault.

This fixes https://savannah.gnu.org/bugs/?53233.

Instead of always calling sctofunc(), it is now only called when
in view mode OR when (after the keystroke's function has been run)
no need for a refresh has been established yet.

Exclude the confusing, pleonastic 'sc' abbreviation from their names.

The new option 'set errorcolor' allows the user to specify the color
combination for the status bar when an error message is displayed.

When 'refresh_needed' is already TRUE, there is no need any more
to check whether it should be set.

[Those first two calls are leftovers from before the time that
reset_multis() morphed into check_the_multis().]

When characters are added via Verbatim Input or by pressing <Tab>,
the prepend flag should be retained, just like when characters are
typed directly.

This fixes https://savannah.gnu.org/bugs/?52956.