gui: move retainaspect handling to the resource ctors

LoadResources should only decide on the resource type,
everything else is handled by the resources themselves.

Change-Id: I30f68293960c23560979f650efc4393992cf5824
diff --git a/gui/resources.hpp b/gui/resources.hpp
index 0ce9684..0eb3267 100644
--- a/gui/resources.hpp
+++ b/gui/resources.hpp
@@ -58,7 +58,7 @@
 class ImageResource : public Resource
 {
 public:
-	ImageResource(xml_node<>* node, ZipArchive* pZip, int retain_aspect);
+	ImageResource(xml_node<>* node, ZipArchive* pZip);
 	virtual ~ImageResource();
 
 public:
@@ -73,7 +73,7 @@
 class AnimationResource : public Resource
 {
 public:
-	AnimationResource(xml_node<>* node, ZipArchive* pZip, int retain_aspect);
+	AnimationResource(xml_node<>* node, ZipArchive* pZip);
 	virtual ~AnimationResource();
 
 public: