Fingerprints, span classes and text path fixes.

* Adds add_fingerprint() to some stuff, adds transfer_fingerprints_to() to walls and computers.
* Converts string paths in circuitboards to type paths, comments out the unused paths.
* Span classes span classes span classes


#1576 is PARTIALLY solved by this. Still needs a bunch of work.

#543 is at least partially solved by this too.