Fix bad and poor unicode mappings, add support for sending Insert
and Pipe.

Toggled using backtick.
Current state is shown in the status bar.

Since we previously couldn't actually *show* the status bar in
ATASCII (or C64) mode, enable that as well.  This means supporting
40-column status bars too.

We still default status bar to off for those modes, because that's
likely what people actually want.

Also, it seems ENTER was broken in ATASCII mode, so fix that as well.
Implements SF feature 61

Save the window position and size when we enter fullscreen, and
restore when we leave... this was a bigger box of worms than
expected since we can get ConfigureNotify events that tell is
"Something" changed, but not be able to know the current window
position.

Just remove the x_get_window_info() and anything else that cares
about the window position and derive it from the ALT-Enter keypress
instead.

At the same time, try to remove as much special-casing for
fullscreen as possible.

Tested under marco and xfwm4... will test under Sommelier "soon"

When using the marco WM, and resizing using ALT-Right-drag, calls to
SDL_SetWindowMinimumSize() result in the top-left corner of the
window moving up and to the left (appears to be by the border size).

To prevent this from being a maddening issue under marco, ensure
we only call SDL_SetWindowMinimumSize() once when the minimum size
changes on the window.

Fixes SF ticket 115, thanks Ragnarok!

While we're hear, ensure the minimium maximum window size holds
the original sized window... we're not interested in downscaling.

Don't always start with _NET_WM_STATE containing
_NET_WM_STATE_FULLSCREEN

Enable PropertyChange events

Adjust x_cvstat.win* when _NET_WM_STATE gets
_NET_WM_STATE_FULLSCREEN added

Don't disable fullscreen in ConfigureNotify handler when
fullscreen is still pending

On expose, always redraw the entire screen.  The calculations were
wrong and with fractional scaling, some of them will always be wrong.

Don't clear the screen when xim is resized.

C allows char* p = '\0' (which is clearly wrong)
C++ does not.

format specifies type 'unsigned short' but the argument has type 'unsigned int'

"unary minus operator applied to unsigned type, result still unsigned"

Even though this same code compiled and worked as expected with GCC.

SANITIZE is not fully supported (or recommended) yet.

FORTIFY will include some performance hits, but those might be offset by -O1
(which is apparently required for _FORTIFY_SOURCE to have any effect).
Prevviosly, DEBUG builds used (implicit -O0).
I'm building and running sbbs on Vertrauen (git.synchro.net) now with FORTIFY.

Set FORTIFY=1 in your localdefs.mk if you wish to have this build option
enabled persistently.

I'm doing builds for my jail (which doesn't have libmosquitto) on
my system that does have it now, so I need to disable it manually.

Mostly (all?) about unchecked return values. Unexpected failures to read or
write some files could've definitely led to some weird bugs.

Don't null-deref h_addr_list.
Return in_addr_t instead of u_long.

warning: ‘maxval’ may be used uninitialized
warning: ‘inch’ may be used uninitialized

Don't deref a null pointer and return an in_addr_t instead of ulong.

Was wrong and therefore causing flickering.

Was not using struts, and was scaling to window size, not aspect
ratio size.

Also, reset struts when not in fullscreen mode.

GDI and X11 still can't be *started* in fullscreen mode though.

Win32GDI currently requires two rects to be available.

- Ensure last is cleared even if we manage external scaling without Xrender
- Free the bitmap rectangle in the same situation
- Make a copy of x_internal_scaling so it's used consistently
  (not mutex protected, and accessed from multiple threads)

If there's already an outstanding rectangle when the blinker thread
wants to send another one, skip it.

This keeps the interface responsive at the cost of some skipped
frames.

ChromeOS (as of Jun 2023) effectivly makes PRIMARY useless.  Just
do the wrong thing and use CLIPBOARD instead.  This makes it much
more likely that SyncTERM selections will clobber CLIPBOARD
unintentionally, but we have no choice... DigitalMan doesn't use
X11 mode solely because ChromeOS sucks at X11.

While we're hacking on that, make a first attempt at a generic
Atom access framework.

The only actual visible change that should occur here is that the
window will not resize larger than will fit on the current desktop
between various WM widgets (panels and menus).  I've been considering
this change for a while, but now that fullscreen support is present,
it doesn't really take anything away.

Just use _NET_WM_STATE protocol for fullscreen... messing around
with the methods is pretty painful.

Because we're not messing with other stuff, we can likely remove
all the code I added to prepare for this. :D

Testing this really highlighted other broken bits, so a bunch of
that has been fixed as well... including the bug that Ragnorok
hadn't reported yet as of last time I looked (corrupted screen when
maximixed).

Or even weirder, u_long?

And dereffing a ulong/u_long pointer where you expect to find an IPv4 address?
Yet even weirder still.

Fix that spit: It appears in_addr_t is defined on all platforms (?), so use
that type instead.

No known sightings of these sites actually being the location of a segfault,
but as we learned from the segfaults in rblchk(), the first entry in the
h_addr_list can be NULL in some cases.