Show the encryption options when running 'fscrypt status' on a
directory.  E.g.:

	Policy:   490515286453d3f7
	Options:  padding:32 contents:Adiantum filenames:Adiantum
	Unlocked: Yes

These were found by a combination of manual review and a custom script
that checks for common errors.

Also removed an outdated sentence from the comment for setupBefore().

Now instead of spawning a seperate thread we alternate between changing
the euid and ruid to both find the keyring and link it to the process
keyring. Note that we also ensure that the user keyring is linked into
the root keyring whenever possible.

This user is used with policies to interface with the keryings and with
protectors to indicate which user's login passphrase should be used to
protectors of type pam_passphrase.

In addition to using callbacks, unlocked Protectors can now directly
unlock a policy. The error codes are updated to make more sense.