add native get/setWeek

[atk]

I wrote a native version of get/setWeek (actually, I copied them over from an old calendar project). I hope you like them.

[coveralls]

Pull Request Test Coverage Report for Build 135

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 134:	0.0%
Covered Lines:	43
Relevant Lines:	43

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💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 137

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

---

Totals
Change from base Build 134:	0.0%
Covered Lines:	43
Relevant Lines:	43

---

💛 - Coveralls

[ODudek]

Please take a look at my comments :)

[atk]

thanks for your comments.

[ODudek]

Please merge with master to pass tests :)

[stevemao]

@ODudek I have restarted the tests against the latest master + this PR and it's green now.