#8 Option to support userid and device map files

[Henrik Nordstrom]

This patch adds a -R option enabling the ability to
remap userids and file types. The feature is controlled
by @filename shadow files next to the actual file
entry. These shadow files contains

uid gid mode type major minor

as many as needed for the file in question (type, major
and minor is only relevant when creating device nodes).

[Henrik Nordstrom]