RFR JDK-8153353: HPACK implementation

[Pavel Rappo]

> On 13 Apr 2016, at 10:10, Chris Hegarty <chris.hegarty at oracle.com> wrote:
> 
> A general comment; Quite a number of classes, especially Encoder and Decoder,
> would benefit from a few relatively lightweight comments, e.g. IntegerReader

I would like to address it after the initial push. If possible. Other than that,
I have updated the implementation:

    http://cr.openjdk.java.net/~prappo/8153353/webrev.01/

There's also a javadoc now:

    http://cr.openjdk.java.net/~prappo/8153353/javadoc.01/

Removed some FIXMEs and TODOs, updated tests.

> StringReader.java
> 
>  reset() can probably just reset its readers, regardless of huffman, since the 
>  readers are always guaranteed to be present ( and reset is minimal ).
> 
>  General comment; in many cases it would be useful to capture, at least, the ‘state’
>  when throwing InternalError.

Done.

> IntegerReader.java
> 
>  reset() assumes that there is no bugs in the code. Should is assign 0 to r,
>  value, and maxValue as well.  

It will be done in the next invocation of 'configure'.

> Q: is it necessary to call configure after reset?

Yes.

> ISO_8859_1.java
> 
>  Sorry, I don’ get 'outstanding'. Are you catching RuntimeException somewhere,
>  or do you expect a user of the Decoder to do some special exception handling ?

Removed. It was a leftover from a failure-atomic behaviour, which is not needed here.

> HpackException.java
> 
>  Do you need this ??? ( FIXME comment )

Removed, thanks. Instead, a sandwich is thrown:

    UncheckedIOException(ProtocolException).