Changes to the File Management Subsystem

When a file is open, the resource container pointer of the file structure is set to the container to which current task is bound. The reference count of the resource container is incremented for each reference of the file structure (this is different from the reference count of the file descriptor since two file descriptors may point to the same file structure). Similar processing happens for the socket() call also.

In the close routine, the reference count of the associated resource container is decremented if there are no more references to the file structure.