add height/width accessor methods

Thumbnailer.go

@@ -73,6 +73,14 @@ func NewThumbnailerEx(Width, Height int, MaxCacheSize uint, of OutputFormat, af
 	return ret
 }
 
+func (this *Thumbnailer) Width() int {
+	return this.width
+}
+
+func (this *Thumbnailer) Height() int {
+	return this.height
+}
+
 func (this *Thumbnailer) RenderFile(absPath string) ([]byte, error) {
 
 	if this.thumbCache != nil {