Deprecating on the road to V5?

[nulltoken]

As seen with #255, we can take small steps now in V4 in order to make the switch to V5 shorter and easier for us to manage.
There are a couple of low hanging issues that we also may also start to tackle.

@linkdotnet One question though, in order to introduce a final API, how would you feel about decorating the "old" API with a [Obsolete] attribute? We would keep both, and drop all the [Obsolete] ones while releasing V5.

Thoughts?

[linkdotnet]

Yes - we can make that in two stages:
Obsolete and treat it as a warning with the new method or approach in the warning message. For v5, if it doesn't impose overhead, we can still have it and mark it as an error.