external: Update system validation method.

Check for EUID of 0 (root user), and for the 'cryptsetup'
utility.

Also print the usage message along with the error.
external: Make mapping setup/removal external.

External to the mounting and unmounting scripts, 'mount.sh' and
'umount.sh', respectively.
Add '.gitignore' file.

Those '.swp' files can be really annoying.
external: Add option to use a keyfile.

The specified password is then hashed and used to create a mapping over
the keyfile, at which point the mapped contents of the keyfile are fed
into the mappings for the specified device.

IMPORTANT: This change is -not- backwards-compatible with older versions
of this utility, because the key-file is straight binary and may contain
newlines, and because specifying a key-file to 'cryptsetup' causes the
utility to skip hashing (in the old version a "sha512" hash was used,
but in the new version this would be ignored even if it was specified);
keep in mind that this means that even if you -don't- use a keyfile, the
hash will be skipped and thus the encrypted device won't mount if it was
formatted using an older version.

Basically, the internal refactoring that I did causes compatibility
issues with older versions; I made the changes because maintaining
backwards-compatibility would have been insane given the extra work and
ugliness it would have added to code not currently being used for
production.
external: Add script to generate a keyfile.
external: Add script for RAID-5 array.

The script can format and assemble a RAID-5 array.
external: Refactor setup script.

Add generic script for RAID-5 and other setups, remove old RAID-5
script.
external: Replace 'password' with 'passphrase'.

For consistency.
external: Fix retry on failed decryption.
Completely refactor scripts.

Remove the 'root'/'external' distinction. This repository will now
include various scripts that I find useful in my Gentoo systems.
Encryption is just one of those things, and it should work on all
distributions, but other scripts will be tailored to Gentoo. The old
external encryption can still be obtained via the 'mount.sh' script.

Add scripts to install Gentoo system and a corresponding initramfs
'init' script. Remove old format/install scripts.