Extract to other than tmp directory and so on

This patch provides followings:

1. Adds a new target ```lzmaSDK-ios``` which generates a static link library ```liblzmaSDK-ios.a``` into the Xcode project. 
By this we can put lzmaSDK as sub-project under another Xcode projects.
2. Extends ```LZMAExtractor``` class with a method ```extract7zArchive:dirName:preserveDir:``` which extracts files to __out of__ the temporary directory.
3. The ```preserveDir:``` says whether we reproduce directory structure from the archive.

My project (https://github.com/keigoi/coq4ios) depends on this patch, so I'm happy if this commit is available from your repo. 

Thank you for your nice work!