wendelin.core: Add pygolang

Starting from 0.14 (aka 2) wendelin.core requires pygolang to be present
both at runtime and at build time.

component/wendelin.core/buildout.cfg

+# SlapOS component for wendelin.core
+
 [buildout]
-extends = ../git/buildout.cfg
+extends =
+  ../pygolang/buildout.cfg
+  ../git/buildout.cfg
+
 parts =
   wendelin.core
 
@@ -7,18 +12,23 @@ parts =
 # wendelin.core installed from released egg from pypi
 [wendelin.core]
 recipe = zc.recipe.egg:custom
-egg = wendelin.core
-
+<= wendelin.core-eggcommon
 
 # wendelin.core installed from latest git version
 [wendelin.core-dev]
 recipe = zc.recipe.egg:develop
-egg = wendelin.core
 setup = ${wendelin.core-repository:location}
-environment = wendelin.core-dev-env
+<= wendelin.core-eggcommon
+
+# common parts in between wendelin.core and wendelin.core-dev
+[wendelin.core-eggcommon]
+egg = wendelin.core
+setup-eggs =
+    ${pygolang:egg}[pyx.build]
+environment = wendelin.core-env
 
-[wendelin.core-dev-env]
-# wendelin.core-dev needs git to build
+[wendelin.core-env]
+# wendelin.core needs git(dev) to build
 PATH = ${git:location}/bin:%(PATH)s