Problem: read/write shada function logic was skipped entirely if it was
detected the shadafile option was set to 'NONE'.
Solution: The filename is now always resolved. When the shadafile option
is set to 'NONE' AND no filename was passed, the filename resolves to an
empty string, which causes the read/write functions to return.
Regardless of whether the option is set to 'NONE', when a filename is
explicitly passed, it gets resolved and the read/write logic is
accessed.