Fixed potential bug in file manager

The previous code wasn't clear, and could result in errors down the road
Also added an error log so we know if this ever happens in the future
fixed bug in file manager

It sometimes sent more files to be hashed than were needed.
Also, added better docs so thi mistake isn't made twice.
logging needless file re-hashes as errors.

This should never happen, so we'll treat it as an error.
Renamed two model objects for clarity

Scan Parents and Scan Objects are now File Objects and Hash Objects
respectfully. The previous names caused problems.
Formalized logging for the GUI portion of Uniquity

We now have a small module that handles logging.
We will build this into an interactive window later.
Forced all worker threads to update when finished

scanner and hasher now push a forced update when finished.