This commit adds logic in configuration file validation that checks that
each account "extra" field is empty after getting it back from the
backend validation. This is to ensure the user doesn't set options that
are invalidly stated in the documentation or by accident.
Closes#135
Configuration error (xxx): the following flags are set but are not recognized: ["index_style"] https://git.meli.delivery/meli/meli/issues/135
- store_sent_mail boolean
Store sent mail after successful submission.
This setting is meant to be disabled for non-standard behaviour in
gmail, which auto-saves sent mail on its own.
