Add WSTRING support

[stlehmann]

Addresses #246

[coveralls]

Pull Request Test Coverage Report for Build 1467908502

• 43 of 46 (93.48%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.2%) to 94.168%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pyads/pyads_ex.py	42	45	93.33%
<!--	Total:	43	46	93.48%	-->

Totals
Change from base Build 1439873570:	0.2%
Covered Lines:	1663
Relevant Lines:	1766

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💛 - Coveralls

[stlehmann]

Looks like there needs to be some more effort here. Strings are handled special in read and write functions. So that needs to be applied to WSTRINGS as well.

[stlehmann]

Now we also need some testing.

[stlehmann]

I just made a Wireshark dump to see if the WSTRING is null-terminated with 1 or 2 Bytes:

Clearly it is two bytes null-termination. So the testserver has to resemble this behaviour.

[kryskool]

Hi @stlehmann

i have an equipement with WSTRING, i try next week this PR

Regards,

[stlehmann]

I just have a use-case where I use WSTRINGs and discovered that adsSumRead and adsSumWrite also need specific WSTRING support

[stlehmann]

Tested the implementation on my PC but couldn't get the test-cases pass, yet. Somehow the encoding is not right. Suggestions are welcome 😊

[stlehmann]

@kryskool did you already do some testing on your setup with this branch?

[stlehmann]

Todo: handle WSTRINGS right in adsSyncReadWriteReqEx2 and in adsSyncWriteControlReqEx