fix: never leave Steam a file it would reinstall itself over

The patch that keeps the script's length was the good path and appending was
the fallback, with -noverifyfiles on everything that starts Steam to cover for
it. That cover does not exist.

Steam checks its files at the shutdown it runs itself, not only at a start
somebody handed arguments to, and that run carries no -noverifyfiles whatever
the session was started with. One wrong length there costs the whole client
package downloaded, extracted and installed again - and the client quits at the
end of it instead of coming up, which is the "Steam just closed itself" that
this was seen as:

    BVerifyInstalledFiles: steamwebhelper.sh is 130 bytes, expected 84
    Update wird heruntergeladen ... Paket wird extrahiert ...
    Aktualisierung abgeschlossen, Steam wird geladen ... Shutdown

So the flag now either fits in the space the comments give back or it is not
written at all, and the status screen says Steam is not patched. No autoscroll
in the interface is a far smaller thing than a client that reinstalls itself.

With no growing patch left to prop up, -noverifyfiles has nothing to do and is
gone with everything that carried it: Steam's launcher entry, its autostart
entry, the shortcuts on the desktop and the ones it writes for single games.
Steam repairs its own installation again. An installation from an older version
is taken back once through the flag scheme, and a patch that version appended
is rebuilt to fit at the next apply - or taken back, if the comments cannot pay
for it.

doc/middleclick-autoscroll.1.scd

@@ -142,23 +142,22 @@ that checks its files finds nothing to repair, and the argument survives
 however Steam was started - from the menu, from a game shortcut, from a
 launcher like Heroic or Lutris, from a terminal.
 
-That is what has to work, because there is no way to make every possible way of
-starting Steam carry an argument. *-noverifyfiles* is the second line rather
-than the first: it covers the case where the script has no comments left to pay
-for the argument and the patch has to grow the file. It goes on Steam's
-launcher entry, on its entry in _~/.config/autostart_, which Steam writes as
-soon as it is set to run at login, and on the shortcuts Steam writes for single
-games, on the desktop and in the menu alike. A game is not an application this
-program has anything to offer and none of them is listed under *Applications*,
-but starting one is a Steam start like any other. The trade-off of the switch
-is that Steam no longer repairs a damaged installation on its own; that is why
-Steam is a switch of its own in the settings.
+That is what has to work, because it is the only thing that does. A patch that
+changes the length is never written, whatever else could be done to cover for
+it: Steam checks its files at the shutdown it runs itself as well as at a start
+it was given arguments for, and that one carries no arguments of anybody's. One
+wrong length costs the whole client package downloaded, extracted and installed
+again, and a client that quits at the end of it instead of coming up.
 
-A patch that does change the size is still held back while the client is
-running: Steam puts its own copy back, the two would only undo each other, and
-the helper is started once, at the start, so patching again would not help that
-session anyway. It goes in at the next apply with Steam closed. A patch that
-keeps the size has nothing to wait for and goes in either way.
+So where the comments cannot pay for the argument, or a client update has
+changed how the helper is started, nothing is written and the status screen
+says Steam is not patched. Nothing goes on Steam's launcher entry, its
+autostart entry or the shortcuts it writes for single games either, and Steam
+goes on repairing its own installation.
+
+An installation patched by an earlier version, which appended where the
+comments were short, is written again to fit at the next apply, or taken back
+if it cannot be made to.
 
 A client update brings a new version of the script. The watcher notices and
 patches it again, and the copy kept for undoing is replaced with the new