implement ADSHardware.__del__ to clean up open WF_SDK references

[leigh-johnson]

Closes #2.

I moved ADSHardware definitions into a module so I didn't have to patch this in two places. Let me know if there was a reason ADSHardware was duplicated and this needs to be reverted. Otherwise, squash + merge at will.

$ python lab_10_template.py                   
[ATTEMPT] Opening ADS device
[SUCCESS] Opened device Analog Discovery 2 handle=c_int(1) addr=4399172504
[ATTEMPT] Closing device Analog Discovery 2 handle=c_int(1) addr=4399172504
[SUCCESS] Closed device  handle=c_int(0) addr=4399172504

I also enabled more verbose traceback on SIGSEGV (seg fault) signals, for follow-up (if needed).