don't invert programatically camera icon, use a white icon set instead

deltachat-ios/Extensions/UIImage+Extension.swift

@@ -3,15 +3,6 @@ import DcCore
 
 extension UIImage {
 
-    func invert() -> UIImage {
-        let beginImage = CIImage(image: self)
-        if let filter = CIFilter(name: "CIColorInvert") {
-            filter.setValue(beginImage, forKey: kCIInputImageKey)
-            return UIImage(ciImage: filter.outputImage!)
-        }
-        return self
-    }
-
     func maskWithColor(color: UIColor) -> UIImage? {
         let maskImage = cgImage!
 

deltachat-ios/View/AvatarSelectionCell.swift

@@ -8,10 +8,7 @@ class AvatarSelectionCell: UITableViewCell {
     var onAvatarTapped: (() -> Void)?
 
     lazy var defaultImage: UIImage = {
-        if let image = UIImage(named: "camera") {
-            return image.invert()
-        }
-        return UIImage()
+        return UIImage(named: "camera") ?? UIImage()
     }()
 
     lazy var badge: InitialsBadge = {