Merge commit 'ab802d5f2319768f8250c1a8819e327e2f9f2843' into master

Update matplotlib-cpp, and make it work with the sandboxed python

Change-Id: Ie9836993f9ab6f8f28877e5958d4b4f119db4632
diff --git a/third_party/matplotlib-cpp/.gitignore b/third_party/matplotlib-cpp/.gitignore
index 7622be7..1c4a1b0 100644
--- a/third_party/matplotlib-cpp/.gitignore
+++ b/third_party/matplotlib-cpp/.gitignore
@@ -33,3 +33,6 @@
 
 # Build
 /examples/build/*
+
+# vim temp files
+*.sw*