Refactor/combine from_bytes and from_stream

[Alon-Alexander]

Fixes #35

• Combined from_stream and from_bytes by creating a as_stream utility.
• Fixed a bug in from_stream where bytes hooks can change the field object (with code which already existed in from_bytes).
• Renamed from_bytes_hook to pre_deserialization_hook but kept the old name there for backward-compatibility.