Method Chaining

[bubbajoe]

Hello again! I was wondering if you would be open to using the method chaining design pattern for the Setters so that changing values can look much better.

Usage example:

cp := astiav.AllocCodecParameters().
                  SetHeight(1).
                  SetHeight(2).
                  SetSampleRate(3)

[asticode]

Hey, I'm not looking for this change right now, but I'll keep the issue open in case that changes