Fix syntax error in memoryview userguide documentation.

Conflicts:
	CHANGES.rst
	docs/src/reference/compilation.rst

let's see if the list order of the python releases makes a difference for the execution order in travis

extract some changes from pull request #504 that seem straight forward and helpful to speed up the travis builds

via distutils comment directives in a Cython source file.

when they are provided as commented distutils directives.