Process streamed data

[schauerte]

Trying to implement #161 by adding a new option without too many overhead. This solution is not optimal:

1. The support for streamed data is added by the generic StreamedOption. This allows the option to be introduced with minimal code changes, but breaks with the option model used so far. Maybe this is OK, because the user has no change to activate this option from the outside: only the new DeserializeStream method uses this wrapper.
2. The place of the check (ExpectEndOfStream) is somewhat strange - see #161 for details.

I would love to see this (or a better) solution merged. Don't hesitate to yell at me, if I've done anything completely wrong or can assist further in implementation.

Many thanks in advance.