use golangci-lint (#876)

* use golangci-lint in Travis CI
* fix linting issues accordingly

.gitattributes

@@ -0,0 +1 @@
+* text=auto

.gitignore

@@ -38,3 +38,6 @@ bin
 
 .idea/
 *.iml
+
+# test-generated files
+cobra/cmd/testproject

.golangci.yml

@@ -0,0 +1,25 @@
+run:
+  deadline: 5m
+
+linters:
+  enable:
+    - deadcode
+    - errcheck
+    - gas
+    - goconst
+    - goimports
+    - golint
+    - govet
+    - ineffassign
+    - interfacer
+    - maligned
+    - megacheck
+    - structcheck
+    - unconvert
+    - varcheck
+  enable-all: false
+  disable-all: true
+#  presets:
+#    - bugs
+#    - unused
+  fast: false

.travis.yml

@@ -1,7 +1,7 @@
 language: go
 
 stages:
-  - diff
+  - lint
   - test
   - build
 
@@ -21,9 +21,10 @@ matrix:
   allow_failures:
     - go: tip
   include:
-    - stage: diff
+    - stage: lint
       go: 1.13.x
-      script: make fmt
+      before_install: go get github.com/golangci/golangci-lint/cmd/golangci-lint@v1.19.1
+      script: golangci-lint run -v
     - stage: build
       go: 1.13.x
       script: make cobra_generator