Python VISA -- control GPIB, USB, Serial Code

Clean up code

- Removed unnecessary trailing \
- Redefined properties using decorators
- Simplified the implementation of some functions/methods
- Removed unnecessary parenthesis

Signed-off-by: Florian Bauer <fbauer.devel@...>

Applied PEP8 style

Signed-off-by: Florian Bauer <fbauer.devel@...>

Removed L suffix in definitions.

The L suffix is not present in Python 3. In Python 2 it is not
necessary if the number is to large to fit in an int.

Signed-off-by: Florian Bauer <fbauer.devel@...>

delete broken test file

visa_study.py seems to be dead code anyway, so lets delete the test
instead of fixing it. Currently it does not run as imports are missing.

Changed except to Python 3 compatible code. Simplified logic in some except.

- changed 'except Exception, x' to 'except Exception as x'
- changed 'raise Exception, x' to raise Exception(x)'

Signed-off-by: Florian Bauer <fbauer.devel@...>

Changed module header to pocoo style.

Signed-off-by: Florian Bauer <flo@...>

almost full coverage of Instrument.read_values

remaining uncovered branch seems to be unreachable

increase test coverage

fix off-by one error in Instrument.read_values

increase test coverage

make most tests pass on python 3

increase test coverage