code objects: add number of kwonly args to number of regular arguments in Py2 (which does not support kwonly arguments for Python functions) to make sure they are still visible for introspection

nogil and more exported functions in numpy.math pxd

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extra : amend_source : 2797e0ad678cc0a33a2548a8a20b00475bc8a21b

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extra : amend_source : 8474ebfc7b6ab33b8cca9e4a478c54b2bee5f2fc

fix in-place assignments of arbitrary objects to variables with inferred Python builtin/extension types

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extra : amend_source : b920a1b9cf4249bb95a7f1a310222080c26dc326

always use UtilityCode.load_cached() for reading dependencies of helpers as it's highly likely that they will be reused by others as well

generate cdef classes and closure classes in a deterministic order to reduce C code churn on regeneration
also fixes a problem where duplicate entries (one used, one unused) could be selected somewhat arbitrarily during type sorting (apparently applied to but worked for memoryview/-slice)