Use a (mostly) hermetic Python interpreter

It still requires python to be installed on the host to run the wrapper
scripts, but it's close to being fully hermetic.

This also requires/enables the following changes, unfortunately all at
the same time:
 * Use a downloaded f2py
 * Use a downloaded scipy/numpy/matplotlib
 * Fix a few things that don't run with the python version in their #!
 * Stop using bazel-generated __init__.py files, because those interfere
   with importing matplotlib nicely

Change-Id: Ife280464613d67cece9587b7d947f0b1d5466d7e
diff --git a/debian/patchelf.bzl b/debian/patchelf.bzl
new file mode 100644
index 0000000..d5cc127
--- /dev/null
+++ b/debian/patchelf.bzl
@@ -0,0 +1,4 @@
+files = {
+    "libstdc++6_4.9.2-10+deb8u1_amd64.deb": "a8f4ef6773b90bb39a8a8a0a5e3e20ca8501de6896204f665eb114d5b79f164f",
+    "patchelf_0.8-2_amd64.deb": "5d506507df7c02766ae6c3ca0d15b4234f4cb79a80799190ded9d3ca0ac28c0c",
+}