keep Python string object references alive across temp cleanup until disposal (e.g. during function calls that take them as arguments)

cython-mode.el: add missing grouping to keyword regexps

* fix font-locking of keyword regexps (matcher was referring to group
  that ceased to exist after 0a7e8d60)

* fix adding customized font-lock-keywords

  Old code behaved bad because it changed an element of a list that was
  compiled into "python-mode" function definition.  This had an
  unfortunate side effect of propagating cython-specific keywords into
  vanilla python buffers.

* fontify new types in ctypedef statements

* add more keywords ("cppclass", "new", "del", etc.)

* add more builtin types ("Py_UNICODE", "ptrdiff_t", etc.)

* fix font-locking of "except?"

* fontify types with font-lock-type-face, not py-class-name-face

Conflicts:
	CHANGES.rst

--HG--
extra : amend_source : 8230801cb0e5cff944c0a7b4cbd0718f28cb344e

--HG--
extra : amend_source : 44298a4bc8ecb8fcc729f7b741ecedd6ad4200b3

document specialisation behaviour when a fused memory-view type occurs multiple times in a function signature

work around bug in fused types code that prevents typing the signature of the runtime dispatch function

fix test: runtime dispatch is done only on the first occurrence of a fused buffer type and later mismatches lead to type failures after the call (which is acceptable since it speeds up the dispatch and leads to an error anyway)