Module file parse API

[Chris Hegarty]

Hi,

A while back it was suggested that it may be useful to define a pull 
parser type API for reading from a module file. I gives separation of 
the parsing of the module file from the writing of it (either installing 
into the module library, or extraction elsewhere ).

I've prototyped such an API and updated the ModuleFile.Reader to use it. 
The first four files in the webrev contain the API, its implementation, 
and a test that demonstrates some sample usage ( extraction of one or 
more classes, listing sections, verifying hashes ). The remainder of the 
changes simply updates some of the tools for installing and handling 
signed modules.

http://cr.openjdk.java.net/~chegar/jigsaw/moduleParser_webrev.00/webrev/

Thanks,
-Chris.