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/y2018/control_loops/python/BUILD b/y2018/control_loops/python/BUILD
index 89f8882..eebbfe2 100644
--- a/y2018/control_loops/python/BUILD
+++ b/y2018/control_loops/python/BUILD
@@ -5,8 +5,10 @@
     srcs = [
         "drivetrain.py",
     ],
+    legacy_create_init = False,
     restricted_to = ["//tools:k8"],
     deps = [
+        ":python_init",
         "//external:python-gflags",
         "//external:python-glog",
         "//frc971/control_loops/python:drivetrain",
@@ -19,8 +21,10 @@
         "drivetrain.py",
         "polydrivetrain.py",
     ],
+    legacy_create_init = False,
     restricted_to = ["//tools:k8"],
     deps = [
+        ":python_init",
         "//external:python-gflags",
         "//external:python-glog",
         "//frc971/control_loops/python:polydrivetrain",
@@ -47,9 +51,11 @@
     srcs = [
         "polydrivetrain_test.py",
     ],
+    legacy_create_init = False,
     restricted_to = ["//tools:k8"],
     deps = [
         ":polydrivetrain_lib",
+        ":python_init",
         "//external:python-gflags",
         "//external:python-glog",
         "//frc971/control_loops/python:controls",
@@ -63,8 +69,10 @@
         "arm_trajectory.py",
         "path_points.py",
     ],
+    legacy_create_init = False,
     restricted_to = ["//tools:k8"],
     deps = [
+        ":python_init",
         "//external:python-gflags",
         "//external:python-glog",
         "//frc971/control_loops/python:controls",
@@ -76,11 +84,14 @@
     srcs = [
         "intake.py",
     ],
+    legacy_create_init = False,
     restricted_to = ["//tools:k8"],
     deps = [
+        ":python_init",
         "//external:python-gflags",
         "//external:python-glog",
         "//frc971/control_loops/python:controls",
+        "@matplotlib",
     ],
 )
 
@@ -104,9 +115,12 @@
         "graph_edit.py",
         "graph_generate.py",
     ],
-    # Sigh, these aren't respected.
     default_python_version = "PY3",
+    legacy_create_init = False,
     srcs_version = "PY3",
+    deps = [
+        ":python_init",
+    ],
 )
 
 py_binary(
@@ -115,7 +129,17 @@
         "graph_codegen.py",
         "graph_generate.py",
     ],
-    # Sigh, these aren't respected.
     default_python_version = "PY2",
+    legacy_create_init = False,
     srcs_version = "PY2",
+    deps = [
+        ":python_init",
+    ],
+)
+
+py_library(
+    name = "python_init",
+    srcs = ["__init__.py"],
+    visibility = ["//visibility:public"],
+    deps = ["//y2018/control_loops:python_init"],
 )