scfg: Two import issues

I'll put both of these in 1 report since they're related to importing.

Issue 1. When using a CD DIRS.TXT list, if you have a directory which subdirectories, scfg will erroneously report a duplicate directory. For example:

$ grep driving DIRS.TXT
/nfs/bbs/bbc/files/games/driving/   BBC:Games:Driving
/nfs/bbs/bbc/files/games/driving/boat/      BBC:Games:Driving:Boat
/nfs/bbs/bbc/files/games/driving/miscellaneous/     BBC:Games:Driving:Miscellaneous
/nfs/bbs/bbc/files/games/driving/motorbike/ BBC:Games:Driving:Motorbike
/nfs/bbs/bbc/files/games/driving_top_down/  BBC:Games:Driving Top Down
/nfs/bbs/bbc/files/games/driving/vertical/  BBC:Games:Driving:Vertical
/nfs/bbs/bbc/files/games/maze/driving/      BBC:Games:Maze:Driving

I got a report about DRIVING being a duplicate directory. There are no duplicates here.

Issue 2. I specified a full pathname to the files, but scfg is assuming that those files are in the /sbbs/data/dirs directory and that is not the case. Parent directory is blank in this case. Maybe an option to use absolute or relative path when importing may be in order to help the sysop properly locate the files.