chore: Add lint script

Makefile

 src_files := src/*.js
 src_dir   := src
 
-.PHONY: all build
+.PHONY: all lint build
 
-all: build
+all: lint build
+
+lint: dist/icons.json
+	./node_modules/.bin/eslint .
 
 build: dist/feather.js dist/feather.min.js
 

package.json

@@ -7,6 +7,8 @@
     "dist"
   ],
   "scripts": {
+    "all": "make",
+    "lint": "make lint",
     "build": "make build",
     "commitmsg": "validate-commit-msg",
     "cm": "git-cz",