Perform sparse select based on $select'ed fields

[hippiehunter]

To improve performance on xfServer we need to pass the $selected fields through to the underlying Synergy Select provider

Aha! Link: https://synergex.aha.io/features/HC-91

[hippiehunter]

This is fixed in #66 and it is only enabled when using xfServer on the actual file io channel