Class _BaseSearchObject

Transfer instance attributes to the given object.

This method is used to transfer attributes set externally (for example
using `setattr`) to a new object created from this one (for example
from slicing).

The reason this method is necessary is because different parsers will
set different attributes for each QueryResult, Hit, HSP, or HSPFragment
objects, depending on the attributes they found in the search output
file. Ideally, we want these attributes to 'stick' with any new instance
object created from the original one.