Python: move interpreters

Move Python interpreters (CPython, PyPy) to same folder and share
layout.

pkgs/development/interpreters/python/cpython/3.4/setup-hook.sh

@@ -0,0 +1,15 @@
+addPythonPath() {
+    addToSearchPathWithCustomDelimiter : PYTHONPATH $1/lib/python3.4/site-packages
+}
+
+toPythonPath() {
+    local paths="$1"
+    local result=
+    for i in $paths; do
+        p="$i/lib/python3.4/site-packages"
+        result="${result}${result:+:}$p"
+    done
+    echo $result
+}
+
+envHooks+=(addPythonPath)