fix decoding of symbol comments

[dgl-cw]

It seems that the comment of a symbol is not encoded in utf-8 but in windows-1252.
I could not find it in the documentation of TwinCAT, but tested it on a Windows 10 machine with TwinCAT3.
It also matches the encoding used here:

pyads/pyads/utils.py

Line 56 in fc7733d

return message.decode("windows-1252").strip(" \t\n\r\0")

The other strings that are decoded with the _get_string method must be ASCII, which is compatible, so changing this here should not be an issue.

[stlehmann]

@dgl-cw thanks for looking into this. Actually it would have been even more helpful to understand the severity of the problem if you raised an issue describing the problem first before providing the PR to fix it. 😉 No worries, I'll create the issue and link the PR to it.

[stlehmann]

fixes #275

[coveralls]

Pull Request Test Coverage Report for Build 1358351849

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 52 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-0.1%) to 93.975%

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Files with Coverage Reduction	New Missed Lines	%
pyads/utils.py	1	95.45%
pyads/ads.py	10	92.7%
pyads/pyads_ex.py	41	90.09%

Totals
Change from base Build 895069826:	-0.1%
Covered Lines:	1622
Relevant Lines:	1726

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💛 - Coveralls