Change Pluck/PluckMap to return slice/map of structs
* #104: Change Pluck/PluckMap to return slice/map of structs (#105) Add common abstract method with EachToStruct processing data Add more tests to cover errs - Remove outdated Get method
* #104: Change Pluck/PluckMap to return slice/map of structs (#105) Add common abstract method with EachToStruct processing data Add more tests to cover errs - Remove outdated Get method