Install from the data files directly from the Diamond DVD, if provided via
CDROM_MOUNT variable. A Diamond install includes the Shadows of
Undrentide, Hordes of the Underdark and Kingmaker expansions. The port
version is 1.61 when using the Diamond DVD.

Remove ARCH requirement, which had been for only i386; let the install of
the Linux base determine if the port is allowed or not. Besides, there is
nothing runnable in this port.

Take maintainership.

Approved by: wxs