Made scalebox the way sway does it

Scaling a wlr_box without rounding can sometimes make the borders not
connected and nice. I noticed this when setting scale in monrules to 1.2

So I've went and copied what Sway did in desktop/output.c but without
having a second function and now using a random rounding macro I found
on the internet so as to not use round from math.h.

s/prev/old

Be consistent with the rest of the code and dwm

remove togglefullscreen keybinding

Distribute it as a patch like in dwm since graphical applications
usually provide their own keybinding; I guess it's only for terminals.

Note that even though these commits don't let you open multiple windows
in fullscreen and cycle between them like in dwm, with just
fullscreennotify spawning new windows or changing tag would still exit
fullscreen automatically, but you would have to toggle fullscreen twice
when switching back to the fullscreen window to enter fullscreen again,
so this is better since it avoids that.

Readme: achieve fullscreen + allow borderpx = 0

Quit fullscreen on new x11 window

After the removal of quitfullscreen() dwl wouldn't compile widh xwayland
enabled because createnotifyx11 was still using the old function

Delete quitfullscreen()

quitfullscreen() was replicating the functionalities of setfullscreen(c,
0)

Reusing setfullscreen() in quitfullscreen() leads to a 3 line function,
which is useless since quitfullscreen() is used once anyway

Keep windows fullscreen after redraw

This fixes the bug that happens when changing workspace (or any time
arrange() is called) where there are fullscreen windows, which are still
fullscreen but leave the space for layer surfaces like waybar (which
should be hidden when going fullscreen)

Also as soon one fullscreen window is found hte function returns to
improve efficiency

Set fullscreen simpler

use m->m (fullscreen on top of layers)

fix typo

Allow borderpx = 0

Toggle fullscreen on all clients

mod+e allows to toggle fullscreen any client, even those who don't
support it themselves

Handle new windows

Windows lose fullscreen state when a new window is created in the same
tag

isfullscreen int

Same fscreen func for xdg and xwayland

Fullscreen xwayland

Unlink fullscreen

Restore windows after fullscreen

Store position and size of windows before going fullscreen. This is more
efficient than arrange() and also works with floating windows

All the clients keep their original position because arrange() isn't
used after quitting fullscreen

No borders on fullscreen windows

Some code has been borrowed from the smartBorders patch

Toggle fullscreen