pcbnew: Adding some missing TypeOf() functions

Missing types were handled by the superclass (in the case of zones)
PCB_CONNECTED_ITEM, which incorrectly returned "true" when testing lines
against zones.

Fixes: lp:1789195
* https://bugs.launchpad.net/kicad/+bug/1789195

pcbnew/class_dimension.h

@@ -84,6 +84,11 @@ public:
 
     ~DIMENSION();
 
+    static inline bool ClassOf( const EDA_ITEM* aItem )
+    {
+        return aItem && PCB_DIMENSION_T == aItem->Type();
+    }
+
     void SetValue( int aValue ) { m_Value = aValue; }
 
     int GetValue() const { return m_Value; }

pcbnew/class_marker_pcb.h

@@ -73,11 +73,15 @@ public:
 
     ~MARKER_PCB();
 
+    static inline bool ClassOf( const EDA_ITEM* aItem )
+    {
+        return aItem && PCB_MARKER_T == aItem->Type();
+    }
+
     /** A scaling factor to create the marker symbol
     */
     static int MarkerScale() {return Millimeter2iu( 0.1 ); }
 
-
     void Move(const wxPoint& aMoveVector) override
     {
         m_Pos += aMoveVector;

pcbnew/class_pcb_target.h

@@ -58,6 +58,11 @@ public:
 
     ~PCB_TARGET();
 
+    static inline bool ClassOf( const EDA_ITEM* aItem )
+    {
+        return aItem && PCB_TARGET_T == aItem->Type();
+    }
+
     void SetPosition( const wxPoint& aPos ) override { m_Pos = aPos; }
     const wxPoint GetPosition() const override { return m_Pos; }
 

pcbnew/class_zone.h

@@ -73,6 +73,12 @@ public:
 
     ~ZONE_CONTAINER();
 
+    static inline bool ClassOf( const EDA_ITEM* aItem )
+    {
+        return aItem && ( ( PCB_ZONE_AREA_T == aItem->Type() ) ||
+                          ( PCB_ZONE_T == aItem->Type() ) );
+    }
+
     /**
      * Function GetPosition
      *