Merge branch 'master' into pluck

.codeclimate.yml

@@ -1,11 +0,0 @@
----
-engines:
-  gofmt:
-    enabled: true
-  govet:
-    enabled: true
-  golint:
-    enabled: true
-ratings:
-  paths:
-  - "**.go"

.gitignore

@@ -1,2 +1,3 @@
 documents
+coverage.txt
 _book

.travis.yml

@@ -0,0 +1,14 @@
+language: go
+
+go:
+  - 1.12.x
+  - tip
+
+before_install:
+  - go get -t -v ./...
+
+script:
+  - go test -race -coverprofile=coverage.txt -covermode=atomic
+
+after_success:
+  - bash <(curl -s https://codecov.io/bash)