Added ->mounted_paths to contain list of path names
Another rewrite.
Main addition is to parse all mountpoint pathnames to see if
they fall within any of the path args; if so then they get their own thread.
Plus some general cleanup of code lint.
Defer get_disk_offset until really needed
(will greatly reduce number of calls)
Added new API to get disk name.
This is really only of cosmetic value (can give nice info about
traverser threading of disks)