Restore swipe to delete tokens in Wallet tab, fixing crash when deleting

AlphaWallet/Tokens/ViewControllers/TokensViewController.swift

@@ -366,8 +366,7 @@ extension TokensViewController: UITableViewDelegate {
     }
 
     func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
-        //Disabled deleting until we figure why it crashes when deleting
-        return false
+        return viewModel.canDelete(for: indexPath.row, section: indexPath.section)
     }
 
     func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {

AlphaWallet/Tokens/ViewModels/TokensViewModel.swift

@@ -77,6 +77,7 @@ class TokensViewModel {
 
     func canDelete(for row: Int, section: Int) -> Bool {
         let token = item(for: row, section: section)
+        guard !token.isInvalidated else { return false }
         if token.contractAddress.sameContract(as: Constants.nativeCryptoAddressInDatabase) {
             return false
         }