Use Luacheck as a pre-commit hook

- Update pre-commit hooks to 2.1.0

.pre-commit-config.yaml

@@ -1,6 +1,14 @@
-- repo: https://github.com/pre-commit/pre-commit-hooks
-  rev: v2.0.0
-  hooks:
-    - id: end-of-file-fixer
-    - id: mixed-line-ending
-    - id: trailing-whitespace
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v2.1.0
+    hooks:
+      - id: end-of-file-fixer
+      - id: trailing-whitespace
+
+      - id: mixed-line-ending
+        args: [--fix=lf]
+
+  - repo: https://github.com/Calinou/pre-commit-luacheck
+    rev: v1.0.0
+    hooks:
+      - id: luacheck

.travis.yml

@@ -11,5 +11,6 @@ install:
   - luarocks install --local luacheck
 
 script:
+  # All linters are run with pre-commit hooks
+  - export PATH="$HOME/.luarocks/bin:$PATH"
   - $HOME/.local/bin/pre-commit run --all-files
-  - $HOME/.luarocks/bin/luacheck .