Prefer dist

Makefile

@@ -8,10 +8,10 @@ usage:
 	@echo "test:  Runs the test suite.\ndoc:   Creates the documentation.\nclean: Removes the documentation, the dependencies and the Composer files."
 
 vendor:
-	@composer install --prefer-source --dev
+	@composer install --dev
 
 update:
-	@composer update --prefer-source --dev
+	@composer update --dev
 
 autoload: vendor
 	@composer dump-autoload