Merge pull request #414 from deltachat/fix_darkmode_contact_cell

fix backgrund color for ContactCells with visible checkmarks

deltachat-ios/View/ContactCell.swift

@@ -60,6 +60,7 @@ class ContactCell: UITableViewCell {
     override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
         super.init(style: style, reuseIdentifier: reuseIdentifier)
         selectionStyle = .none
+        backgroundColor = DcColors.chatBackgroundColor
         contentView.backgroundColor = DcColors.chatBackgroundColor
         setupSubviews()
     }