#1 Several fixes to zip.rb

[Kristoffer Lundén]

I am attaching a new zip.rb containing the following
fixes:

Lines 469 and 971 gave warnings when running programs
that used zip.rb. The fix is simply to put parenthesises
around the parameters to yield.

Lines 176 and 625 has had the parameter changed to -
Zlib::MAX_WBITS as mentioned in a bug report on this
site.

Also, when calling extract with a block for handling
already existing files/directories, only directories got the
parameters when this happened, when a file already
existed the block was called without parameters. The
changes to lines 837, 908 and 909 fixes this problem.
Basically, it only passes around the entry (which it didn't
before) and calls the procedure with entry and path.
This makes it for instance possible to have a handler
that asks a user interactively what to do if a file already
exists.

As you can see this is just minor fixes, but all of them
were relevant to me when I was using the library, so I
hope others will have use of this too.

-- Kristoffer

[Kristoffer Lundén]

zip.rb with changes applied