Faster shopfloor-setup sync, prompt spacing, XP-era test client

- Deploy shopfloor-setup with rsync instead of the copy module: the
  ~4 GB tree took about 4 minutes on every re-run because copy checksums
  each file. rsync transfers only changes; changed only when it did.
- iPXE drops a trailing space, so 'Machine number:' ran into the typed
  digits. The space now comes from a hex 20 setting.
- tests/vm: pxetest-xp is a permanent client (SeaBIOS, qemu32 32-bit CPU,
  rtl8139, 1 GiB, IDE disk) for the i686 Clonezilla path; start.sh xp.
  Only one client may run at a time across all three.

playbook/ipxe/GetPxeScript.aspx

@@ -69,7 +69,10 @@ goto cz_machine
 # iPXE cannot check characters: pxe-cz.sh accepts letters, digits and dash
 # and asks again there. Empty: ask again. Esc / Ctrl-C: back to the menu.
 echo
-echo -n Machine number: && read czmachine || goto menu
+# iPXE drops a trailing space from a command line, so the space after the
+# colon comes from a setting (0x20) rather than the literal text.
+set sp:hex 20
+echo -n Machine number:${sp:string} && read czmachine || goto menu
 isset ${czmachine} || goto cz_machine
 # Same CPU check as the manual entry below (cpuid --ext 29 = 64-bit).
 cpuid --ext 29 && goto cz_auto64 || goto cz_auto32