Allow alternate totp format (#523)

Fixes #495

app/src/main/java/com/zeapo/pwdstore/PasswordEntry.kt

@@ -83,6 +83,9 @@ class PasswordEntry(private val content: String) {
             if (line.startsWith("otpauth://totp/")) {
                 return Uri.parse(line).getQueryParameter("secret")
             }
+            if (line.toLowerCase().startsWith("totp:")) {
+                return line.split(": *".toRegex(), 2).toTypedArray()[1]
+            }
         }
         return null
     }