Added
* Update `Customer` record fields/record refs for 2021.2. (535)
The following were moved from `fields` to `record_refs`: `buying_reason`, `buying_time_frame`, `campaign_category`, `image`, `opening_balance_account`, `pref_cc_processor`, `representing_subsidiary`, `sales_group`, `sales_readiness`
The following were removed as `fields` since their sublist class is not yet implemented: `download_list`, `group_pricing_list`, `item_pricing_list`
* Add search-only fields to `Customer` (535)
* Add `attach_file` action to `Customer` records (544)
* Add `update` action to `File` records (544)
* Expose `errors` after calls to `delete` action (545)
* Add `update_list` action where missing on supported item records (546)
* Add `proxy` attribute to `NetSuite::Configuration` to set a proxy used by the savon client (547)
Fixed
* Ignore `after_submit_failed` status details (>= 2018.2) when collating errors in add action (550)
* Add `NullFieldList` to `SalesOrder` (552)
* Add thread safety to NetSuite configuration and utilities (549)
Breaking Changes
* Rename `CustomerSubscriptionsList` to `SubscriptionsList` and `CustomerSubscription` to `Subscription` to match NetSuite naming (535)