Synchronize localtime between Chrome OS and host OS:
 - bindmount /var/lib/timezone
 - During installation, link /etc/localtime to /var/lib/timezone/localtime
Update /etc/timezone in enter-chroot, by guessing its value from
the current /etc/localtime.
Add -T to the creation of /etc/localtime symlink, in the unlikely
case where /etc/localtime is a directory.
Revert "Update /etc/timezone in enter-chroot, by guessing its value from"

After discussion, updating /etc/timezone is not necessary, and even
possibly harmful, as Ubuntu would erase /etc/localtime upon tzdata
upgrade if /etc/timezone exists.

This reverts commit 94566f369f2e34ca2688b8584ff3c6955561b131.
Document why we are removing /etc/zoneinfo from the guest OS.
Check that the link /etc/localtime points to is a valid timezone in the guest OS.
Simplify timezone sanity check.
ChromeOS -> Chromium OS
Properly copy symlinks when installing files.
Add double-e parameter to mount-chroot to change the passphrase.
Support passing two -e's to the installer.
Add edit-chroot command for managing chroots.

delete-chroot is now just a symlink to edit-chroot.
Don't chmod copied symlinks.
@drinkcat: Use useradd instead of adduser to avoid pointless prompts.

Thanks, @drinkcat!
Move timezone sync earlier, into core target.
No, we don't want to run hddtemp as a daemon.
Move ubuntu to separate directory.
New wrapper installer script.
First working Arch Linux version. More testing needed.
Support for "touch" target.