Re-organised top sheet.

Lots of parts just changed their component designator. I had
to patch up the PCB manually, but now it imports from the schematic
OK.

Also adds two PSU rails for the RTC (so you can pick DS1307
which is a 5V part, or MCP7940N which is a 3.3V part).

Author: jonathanpallant

Kicad/expansion_slots.kicad_sch

@@ -1375,7 +1375,7 @@
     (effects (font (size 1.27 1.27)) (justify right))
     (uuid df6ad5f4-de15-4501-a705-dbcff656473a)
   )
-  (hierarchical_label "~{IRQ}" (shape output) (at 90.17 72.39 180)
+  (hierarchical_label "~{IRQ_IO}" (shape output) (at 90.17 72.39 180)
     (effects (font (size 1.27 1.27)) (justify right))
     (uuid f2862a47-46e9-40a8-a47e-389c7b661d9c)
   )