Bringing all file operations together into one place

[Alan Bateman]

One of the things that I've been looking at recently is the file system 
API and to see how it might evolve in the future, post jdk7. One 
confusing thing is that the file operations are currently split over 
several classes. At it stands, if a file operation requires new support 
from the provider implementation then it is added to the Path class, if 
it is independent of the provider it can be defined by the Files class, 
file attribute helper methods are defined by the Attributes class. This 
needs to be cleaned up so that it's clear and obvious where to add new 
file operations in the future. To that end, I have an update to the API 
[1] that moves all the file operations into the Files class and removes 
the Attributes class. For the most part, the methods defined by Files 
just delegate to the FileSystem associated with the Path or are 
implemented in terms of other methods. The alternative moves everything 
to Path but that is much less satisfactory and results in a huge class 
of path and file operations. Another advantage of having Path only 
define path methods is that it opens the possibility of look at 
interfaces again, esp. with extension methods potentially coming in 8.

There are a couple of other small updates too. The readXXXFileAttributes 
methods to read attributes in bulk have been replaced with a single 
readAttributes method that takes a type token to specify the required 
attributes - this is something that Joe Darcy suggested. There are also 
a few new convenience methods for simple/common cases.

Feedback welcome!

-Alan

[1] http://openjdk.java.net/projects/nio/javadoc