Starting merge of @felixleong's code

I'm gonna name these "sprues" and do it a tad different than him, but it'll be mostly his code

lib/squib/sprues/builtin/a4_euro_card.yml

@@ -0,0 +1,42 @@
+---
+sheet_width: 210mm
+sheet_height: 297mm
+card_width: 59.0mm
+card_height: 92.0mm
+cards:
+  - x: 16.5mm
+    y: 10.0mm
+  - x: 75.5mm
+    y: 10.0mm
+  - x: 134.5mm
+    y: 10.0mm
+  - x: 16.5mm
+    y: 102.0mm
+  - x: 75.5mm
+    y: 102.0mm
+  - x: 134.5mm
+    y: 102.0mm
+  - x: 16.5mm
+    y: 194.0mm
+  - x: 75.5mm
+    y: 194.0mm
+  - x: 134.5mm
+    y: 194.0mm
+crop_line:
+ lines:
+ - type: :vertical
+   position: 16.5mm
+ - type: :vertical
+   position: 75.5mm
+ - type: :vertical
+   position: 134.5mm
+ - type: :vertical
+   position: 193.5mm
+ - type: :horizontal
+   position: 10.0mm
+ - type: :horizontal
+   position: 102.0mm
+ - type: :horizontal
+   position: 194.0mm
+ - type: :horizontal
+   position: 286.0mm

lib/squib/sprues/builtin/a4_poker_card_8up.yml

@@ -0,0 +1,40 @@
+---
+sheet_width: 297mm
+sheet_height: 210mm
+card_width: 63.0mm
+card_height: 88.0mm
+cards:
+- x: 22.5mm
+  y: 10.0mm
+- x: 85.5mm
+  y: 10.0mm
+- x: 148.5mm
+  y: 10.0mm
+- x: 211.5mm
+  y: 10.0mm
+- x: 22.5mm
+  y: 98.0mm
+- x: 85.5mm
+  y: 98.0mm
+- x: 148.5mm
+  y: 98.0mm
+- x: 211.5mm
+  y: 98.0mm
+crop_line:
+  lines:
+  - type: :vertical
+    position: 22.5mm
+  - type: :vertical
+    position: 85.5mm
+  - type: :vertical
+    position: 148.5mm
+  - type: :vertical
+    position: 211.5mm
+  - type: :vertical
+    position: 274.5mm
+  - type: :horizontal
+    position: 10.0mm
+  - type: :horizontal
+    position: 98.0mm
+  - type: :horizontal
+    position: 186.0mm

lib/squib/sprues/builtin/a4_poker_card_9up.yml

@@ -0,0 +1,42 @@
+---
+sheet_width: 210mm
+sheet_height: 297mm
+card_width: 63.0mm
+card_height: 88.0mm
+cards:
+- x: 10.5mm
+  y: 10.0mm
+- x: 73.5mm
+  y: 10.0mm
+- x: 136.5mm
+  y: 10.0mm
+- x: 10.5mm
+  y: 98.0mm
+- x: 73.5mm
+  y: 98.0mm
+- x: 136.5mm
+  y: 98.0mm
+- x: 10.5mm
+  y: 186.0mm
+- x: 73.5mm
+  y: 186.0mm
+- x: 136.5mm
+  y: 186.0mm
+crop_line:
+  lines:
+  - type: :vertical
+    position: 10.5mm
+  - type: :vertical
+    position: 73.5mm
+  - type: :vertical
+    position: 136.5mm
+  - type: :vertical
+    position: 199.5mm
+  - type: :horizontal
+    position: 10.0mm
+  - type: :horizontal
+    position: 98.0mm
+  - type: :horizontal
+    position: 186.0mm
+  - type: :horizontal
+    position: 274.0mm

lib/squib/sprues/builtin/a4_usa_card.yml

@@ -0,0 +1,42 @@
+---
+sheet_width: 210mm
+sheet_height: 297mm
+card_width: 56.0mm
+card_height: 87.0mm
+cards:
+- x: 21.0mm
+  y: 10.0mm
+- x: 77.0mm
+  y: 10.0mm
+- x: 133.0mm
+  y: 10.0mm
+- x: 21.0mm
+  y: 97.0mm
+- x: 77.0mm
+  y: 97.0mm
+- x: 133.0mm
+  y: 97.0mm
+- x: 21.0mm
+  y: 184.0mm
+- x: 77.0mm
+  y: 184.0mm
+- x: 133.0mm
+  y: 184.0mm
+crop_line:
+  lines:
+  - type: :vertical
+    position: 21.0mm
+  - type: :vertical
+    position: 77.0mm
+  - type: :vertical
+    position: 133.0mm
+  - type: :vertical
+    position: 189.0mm
+  - type: :horizontal
+    position: 10.0mm
+  - type: :horizontal
+    position: 97.0mm
+  - type: :horizontal
+    position: 184.0mm
+  - type: :horizontal
+    position: 271.0mm