Small changes to File, big changes to Test

_File:
- added extra output to __str__

FieldTest_File:
- added more info to __str__ output

_Measurement:
- __init__ now takes a tuple of size and speed units

_Test:
- added/renamed some class variables
- __init__ determines connection type
- more reliably determined connection location
- MeasuringFmt is now a tuple (size, speed)
- improved __str__ output

TCP_Test and UDP_Test:
- prepping for update based on changes made in _Test

basic_utils:
- added another error type