Use `CommandManager` select vertex methods in `SelPrevVertexCmd`

src/Commands/SelPrevVertexCmd.cpp

@@ -3,17 +3,17 @@
 namespace ofx {
 namespace piMapper {
 
-SelPrevVertexCmd::SelPrevVertexCmd(BaseSurface * s){
-	_surface = s;
+SelPrevVertexCmd::SelPrevVertexCmd(SurfaceManager * sm){
+	_surfaceManager = sm;
 }
 
 void SelPrevVertexCmd::exec(){
-
+	_surfaceManager->selectPrevVertex();
 }
 
 void SelPrevVertexCmd::undo(){
 	ofLogNotice("SelPrevVertexCmd", "undo");
-	
+	_surfaceManager->selectNextVertex();
 }
 
 } // namespace piMapper

src/Commands/SelPrevVertexCmd.h

@@ -1,7 +1,7 @@
 #pragma once
 
 #include "BaseCmd.h"
-#include "BaseSurface.h"
+#include "SurfaceManager.h"
 
 class ofxPiMapper;
 
@@ -11,12 +11,12 @@ namespace piMapper {
 class SelPrevVertexCmd : public BaseUndoCmd {
 
 	public:
-		SelPrevVertexCmd(BaseSurface * s);
+		SelPrevVertexCmd(SurfaceManager * sm);
 		void exec();
 		void undo();
 
 	private:
-		BaseSurface * _surface;
+		SurfaceManager * _surfaceManager;
 
 };