fix some HTML issues in annotation file

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extra : transplant_source : gx%EB%08%DA%5D%B2-lzq%ED%3A%A9Xn%B3%EAX%01
make code blocks open on first click instead of second

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extra : transplant_source : %C6%DAZ%C5%05%2A%ADhrA1%86X%84S%C2%17%23I-
minor code cleanup

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extra : transplant_source : %D7%EC%163%08%A9N%E1%94%95%97%3A.%E94%D0%7C%AE%F3%85
fix declaration of PyBuffer_FillInfo()

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extra : transplant_source : %83%FAO%836%1Dw%5B%E3%94%E1%E6%7F%0C%EF%D9E%DE%D2%A2
move misplaced PyObject_Format() C-API declaration to right .pxd file

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extra : transplant_source : Zp%DC%BB8%03%B2%D6%A3%09q%13%25%17%AD6%17%25%1FU
some missing math.h functions and macros in math.pxd

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extra : transplant_source : %D8%3C%96Q%8A%23%1E%F4%FF%3E%DF%7D%18%17%5E%00%12%C8%FCk
Some math.h fixes, c99 isX macros.

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extra : transplant_source : %A2%F5%D0%5C%3B%7E%E9%BC%A3s%29%BBr%D7%06N%BC%88%F4%BB
Fix several MS compiler warnings.

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extra : transplant_source : 1_%40L%92%DD%AC%FAM%9C%F5%92%80%D4%B3%BA%DEL%F2%D4
move some build docs from user guide to reference to reduce redundancy

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extra : transplant_source : a%5D%AC%9A%18%7B%DD%94%7D%20%22%CC%CB%D39%AE%10%C0%8FC
merge overview page from user guide into quickstart and delete it

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extra : transplant_source : p%B5S%9517%99%11%94%06%B9j%FC%1BZt%F28_%D5
move Cython tutorial from user guide to tutorial part

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rename : docs/src/userguide/tutorial.rst => docs/src/tutorial/cython_tutorial.rst
extra : transplant_source : %97%AD%B6%9D%2A%0F%11a-%9F%F2%C6%BBOe%95%CD%CAX9
Add memory allocation from wiki.

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extra : transplant_source : %93%13%FC%AA%07x%7D%14%F7E%D8%C0%01%DC%40%1C%BF%0F%F6S
Added limitations from wiki.

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extra : transplant_source : %AE%AE%EB%26%11d%C3%C4%BD/e%F6%08%08%40z%DD%C4%D1%E0
mention PyMem_*() C-API functions in memory allocation tutorial
merge branch 0.19.x into master