Merge remote-tracking branch 'upstream/master' into category_tree_experimental

Author: carols10cents

.travis.yml

@@ -49,14 +49,14 @@ matrix:
   allow_failures:
     - rust: nightly
   include:
-    - rust: nightly-2018-03-31
+    - rust: nightly-2018-06-26
       script:
-        - cargo install --force clippy --vers 0.0.191
+        - cargo install --force clippy --vers 0.0.210
         - cargo clippy
     - rust: stable
       script:
         - rustup component add rustfmt-preview
-        - cargo fmt -- --write-mode=diff
+        - cargo fmt -- --check
         - cargo build
         - cargo test
         - npm install