Add Makefile with lint and format targets for better DX

Using shellcheck and shfmt.

.editorconfig

@@ -10,3 +10,16 @@ indent_size = 2
 indent_style = space
 insert_final_newline = true
 trim_trailing_whitespace = true
+
+[Makefile]
+indent_size = 4
+indent_style = tab
+
+# These are shfmt extensions
+# See: https://github.com/mvdan/sh
+
+[bin/*]
+shell_variant = posix
+binary_next_line = true
+switch_case_indent = true
+space_redirects = true

.gitignore

@@ -0,0 +1 @@
+.tmp/

CHANGELOG.md

@@ -6,6 +6,7 @@
 - Improve self-upgrade script
 - Improve previous installation detection on g-install
 - Make self-upgrade throw if g was not installed via g-install
+- Add Makefile with lint and format targets for better DX
 
 ## 0.6.0 - 2019-10-13
 

Makefile

@@ -0,0 +1,40 @@
+.POSIX:
+
+PLATFORM=$(shell uname -s | tr '[:upper:]' '[:lower:]')
+ARCH=$(shell uname -m | tr '[:upper:]' '[:lower:]')
+ARCH_SIMPLE=$(shell echo $(ARCH) | sed 's/x86_64/amd64/g')
+
+SHELLCHECK_VERSION=0.7.0
+SHELLCHECK_DOWNLOAD_URL=https://shellcheck.storage.googleapis.com/shellcheck-v$(SHELLCHECK_VERSION).$(PLATFORM).$(ARCH).tar.xz
+SHELLCHECK_TAR_PATH=shellcheck-v$(SHELLCHECK_VERSION)/shellcheck
+
+SHFMT_VERSION=3.0.0
+SHFMT_DOWNLOAD_URL=https://github.com/mvdan/sh/releases/download/v$(SHFMT_VERSION)/shfmt_v$(SHFMT_VERSION)_$(PLATFORM)_$(ARCH_SIMPLE)
+
+.PHONY: prepare
+prepare: .tmp/shellcheck .tmp/shfmt
+
+.PHONY: lint
+lint: prepare
+	@./.tmp/shellcheck bin/*
+	@./.tmp/shfmt -d bin/*
+
+.PHONY: format
+format: prepare
+	@./.tmp/shfmt -w bin/*
+
+.tmp/shellcheck:
+	@echo "Downloading shellcheck"
+	@echo
+	@mkdir -p .tmp
+	@curl '$(SHELLCHECK_DOWNLOAD_URL)' | tar -xJO '$(SHELLCHECK_TAR_PATH)' > .tmp/shellcheck
+	@chmod +x .tmp/shellcheck
+	@echo
+
+.tmp/shfmt:
+	@echo "Downloading shfmt"
+	@echo
+	@mkdir -p .tmp
+	@curl --location '$(SHFMT_DOWNLOAD_URL)' > .tmp/shfmt
+	@chmod +x .tmp/shfmt
+	@echo