Implemented hashing of the files represented in the file tree structure.
Started implementing indexing functions in FileIndex.java that will help accomplish some of the goals of this projectand it's application (finding duplicate files by their contents and by their filenames. Added two file properties to FilePropertyContainer, isReadable and isWritable. They will be used to ensure that filewise operations are permitted before trying to do them, so thrown errors can be avoided. Such operations include generating a hash by reading a file's contents, but of course the file must be readable by the user running the application. A message is thrown 'check file permissions' if an operation is attempted but blocked/aborted because of the readable/writable status of the file. Implemented a method generateFileIndex() in FileTree and FileTreeNode that will return a list collection of all the files under a certain node. It is a recursive call, so child nodes' files will also be included.