bind callback to connection (dbosoft#48) (dbosoft#50)

pin Dbosoft.Functional version (3.x) (dbosoft#52)

pinned Dbosoft.Functional to >= 1.0 < 2.0

bind callback to connection (dbosoft#49)

removed the simplified RfcContext constructor (4.x) (dbosoft#45)

bad design decision - keep it straight is it was in past and use one constructor
instead added a ConnectionBuilder to fluent build options for connection and runtime.

Update of references (dbosoft#40)

* replaced gitversiontask with GitVersion.MSBuild
* updated JetBrains.Annotations

fix row iterator (dbosoft#37)

* check for null pointer handles

* don't move row in iterator if MoveToFirstTableRow fails

fix rowiterator (3.x branch) (dbosoft#36)

* check if returned handle is valid pointer
* table iterator: don't  read row if MoveToFirstTableRow fails

prefer EitherAsync instead of Task<Either<>> (dbosoft#33)

* prefer EitherAsync instead of Task<Either<>>
* update of dbosoft.functional package

ensure callback handler is not garbage collected (dbosoft#24)

ensure callback handler is not garbage collected (dbosoft#24)