Adding cython v0.20.2 in third-party.

third_party/cython/src/Makefile

+PYTHON?=python
+REPO = git://github.com/cython/cython.git
+
+all:    local 
+
+local:
+        ${PYTHON} setup.py build_ext --inplace
+
+TMPDIR = .repo_tmp
+.git: .gitrev
+        rm -rf $(TMPDIR)
+        git clone -n $(REPO) $(TMPDIR)
+        cd $(TMPDIR) && git reset -q "$(shell cat .gitrev)"
+        mv $(TMPDIR)/.git .
+        rm -rf $(TMPDIR)
+        git ls-files -d | xargs git checkout --
+
+repo: .git
+
+
+clean:
+        @echo Cleaning Source
+        @rm -fr build
+        @rm -f *.py[co] */*.py[co] */*/*.py[co] */*/*/*.py[co]
+        @rm -f *.so */*.so */*/*.so 
+        @rm -f *.pyd */*.pyd */*/*.pyd 
+        @rm -f *~ */*~ */*/*~
+        @rm -f core */core
+        @rm -f Cython/Compiler/*.c
+        @rm -f Cython/Plex/*.c
+        @rm -f Cython/Runtime/refnanny.c
+        @(cd Demos; $(MAKE) clean)
+
+testclean:
+        rm -fr BUILD
+
+test:   testclean
+        ${PYTHON} runtests.py -vv
+
+s5:
+        $(MAKE) -C Doc/s5 slides