Introduce proper support for non-shp sprites in cursors and ShpImageWidget.

mods/cnc/cursors.yaml

@@ -4,7 +4,7 @@
 
 
 Cursors:
-	mouse2: cursor
+	mouse2.shp: cursor
 		scroll-t:
 			start:1
 		scroll-tr:
@@ -114,7 +114,7 @@ Cursors:
 			start:154
 			length:24
 
-	mouse4:cursor
+	mouse4.shp:cursor
 		move:
 			start:0
 			length:8
@@ -125,7 +125,7 @@ Cursors:
 			start:0
 			length: 8
 
-	attackmove:cursor
+	attackmove.shp:cursor
 		attackmove:
 			start:0
 			length:8
@@ -138,7 +138,7 @@ Cursors:
 			start:13
 			length:1
 
-	mouse3: cursor2
+	mouse3.shp: cursor2
 		enter-blocked:
 			start:212
 			length:1
@@ -170,7 +170,7 @@ Cursors:
 			start:213
 			length:1
 
-	nopower: cursor
+	nopower.shp: cursor
 		powerdown-blocked:
 			start:0
 			length: 1