KTable#filter(K,V => Boolean, Materialized) is called recusively on KTableS

[mtranter]

Calling filter(K,V => Boolean, Materialized) causes stack overflow. Looks due to strange implicit coversion of inner property.

Probably similar to: #41

I am using Scala 2.12.4.

Simple Gist here to demonstrate: https://gist.github.com/mtranter/3fc613d63ce584adba28bc81e1622331

[mtranter]

Submitted PR here: #55

[debasishg]

Fixed.