Fix all whitespace -- alternative approach

[dpoetzsch]

I implemented an alternative approach that avoids reparsing the output for newlines in the IndentWriter.

Basic idea was to use a specialized IndentWriter everywhere. This way, we can call the newline-specialized method writeLines in appendText.

Note however, that besides changing a lot of interfaces this implementation made the implementation of the LatchedWriter a lot more complicated because it also needs to be newline aware in its buffer.

[spullara]

I checked out this branch and ran the spec tests and it looks like whitespace differences still occur. Does the branch still require it to be enabled?

[dpoetzsch]

This branch is not perfect yet. It shows how a tiny bit of performance could be achieved by adding a lot more complexity.

I just wanted to show how we might be able to avoid reparsing the output, but because of the new complexities with async writers I personally would prefer the solution of #215.

So I close this.