Use inodeFs as layer between FileSystemConnector and FileSystem.

This further prepares fsInode as an intermediate layer between raw and
path filesystems.

Only fsInode maintains Parent links. This prepares for inserting
a layer between RawFileSystem and FileSystem, which can define
filesystems in terms of inodes.

rm from coreutils < 8.0 is relying on synchronization between a read
of and unlink within a directory.  Posix does not require such
synchronization.

For making the test pass, install coreutils 8.0 or later.

Fixing this test will require changes to the opendir/readdir API.

as root. This is important especially when LoopbackFileSystem
is used in combination with AutoUnionFs and the root one of
the overlays is a symlink - in that case we don't want to
link out of the overlay directory structure.

Allows autoconfiguration of symlinked directories

the root path.

within 32-bits.

This is needed to deal with 32-bits programs that use stat().  If the
inode number exceeds 32 bit, that will return an ERANGE error.