Fix footprints for Mini PCIe and switches

(set pads for mounting and case to GND)
Set PCB to 4 layer with 0.5 OZ (0,017mm) copper on the inner layers
Start sorting the footprints on the PCB
TO-DO: check footprints of Y1 and Y2, they seem way too large

Hardware/KiCad/DIY_Router.kicad_prl

@@ -77,6 +77,8 @@
       false,
       false,
       false,
+      false,
+      false,
       false
     ],
     "col_order": [
@@ -89,7 +91,9 @@
       6,
       7,
       8,
-      9
+      9,
+      10,
+      11
     ],
     "col_widths": [],
     "custom_group_rules": [],