Keep the two Windows executables from being one file

Windows matches a filename without regard to its case, so Dikte.exe and
dikte.exe were one file in the installation directory: PyInstaller wrote
the console build second and that is the only one that landed. Every
launcher then opened a console window behind the tray, and closing it
killed the application.

The console one is dikte-cli.exe now, which the setup's shim names. The
build reads the PE subsystem of both afterwards, since a filesystem that
keeps the two names apart is exactly what the check would run on
otherwise.

README.windows.md

@@ -21,7 +21,9 @@ entry, a `dikte` command and, unless you untick it, a start at sign-in. It is
 signed with no certificate, so SmartScreen offers only **Don't run** until you
 press **More info**. Add/Remove Programs uninstalls it, and `dikte integrate`
 and `dikte integrate --remove` are the sign-in entry on its own, for changing
-your mind about that later.
+your mind about that later. The `dikte` command is the same file install.ps1
+writes, so over a checkout the setup takes it over and uninstalling takes it
+away; run install.ps1 again to get the checkout's back.
 
 From a checkout instead: