Add statement to close sevenZFile object

[sebasblancogonz]

#4 I just added a line to close the SevenZFile object. A simple call to the close() method of the class.
I've tested it on a local project and it works like a charm!

Hope it fits!

[simonnagl]

Thank you for your first pull request. I really appreciate your work done. Can you please use withCloseable instead of calling close directly? This will close the SevenZFile even if an exception is thrown while unzipping.

[sebasblancogonz]

Thank you so much for your advice! For sure will never forget it! Is it correct now?

[simonnagl]

I just implemented the fix myself. The problem with your fix is that sevenZFile and entry are defined outside the auto-close scope.
This is no problem for now, but the code is now open for bugs. If someone accesses one of the variables after the scope, unexpected things might happen.