make it easier for the C compiler to prune some useless error checking code in cython.array constructor

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extra : amend_source : 4d5d9dc96421710652afe8614c9f32db26cc88c1

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extra : amend_source : 685e555a2102e496280287b3b7605d67d694ff40

use CPython heap memory allocation for memory views where possible (outside of nogil sections) as it tends to be faster than plain malloc()

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extra : amend_source : 8ea50b285fc8d55899450c179754d7c2aba94591

some minor changes

fix deprecated imports in "Unicode and passing strings" tutorial

make reference from memory allocation tutorial to memory views and array.array support more prominent

get rid of __signature__ property for cyfunctions again as inspect.py in Py3.4 can do the same thing more efficiently all by itself now (only commenting it out because it could potentially become a feature again at some point)

Allow docstrings on cdef classes in .pxd files

Added patch from Nikita to properly parse extension type attribute docstrings in PXD files as well as source files