Command line options should take native paths relative to cwd
The -out option currently takes a path that is relative to
/home, i.e., it's an FS2 path. It is not possible to direct output to any native file.
However, the convention about paths passed via the command line is that they are relative to the current working directory. We should standardize the interpretation of all applicable paths passed via the command line according to this convention.
de::CommandLine should be updated with a convenience mechanism to provide FS2 files mapped to provided locations.
FS2 should provide a convenience mechanism for creating a file that points to a custom location in the native file system. This custom file would not belong to any feed, or it could belong to some special "preset locations" feed.