Introduce code formatter

.editorconfig

@@ -2,7 +2,7 @@ root = true
 
 [*]
 charset = utf-8
-indent_style = tab
+indent_style = space
 indent_size = 4
 end_of_line = lf
 insert_final_newline = true

rebar.config

@@ -1,68 +1,75 @@
 %% -*- mode: erlang; -*-
 {require_min_otp_vsn, "21"}.
 
-{erl_opts,
- [fail_on_warning,
-  debug_info,
-  warn_unused_vars,
-  warn_unused_import,
-  warn_exported_vars]}.
+{erl_opts, [
+    fail_on_warning,
+    debug_info,
+    warn_unused_vars,
+    warn_unused_import,
+    warn_exported_vars
+]}.
 
-{xref_checks,
- [undefined_function_calls,
-  undefined_functions,
-  locals_not_used,
-  %% exports_not_used,
-  deprecated_function_calls,
-  deprecated_functions
- ]}.
+{xref_checks, [
+    undefined_function_calls,
+    undefined_functions,
+    locals_not_used,
+    %% exports_not_used,
+    deprecated_function_calls,
+    deprecated_functions
+]}.
 
 {project_plugins, [
+    erlfmt,
     rebar3_proper
 ]}.
+{erlfmt, [
+    write,
+    {print_width, 120},
+    {files, [
+        "{src,include,test}/*.{hrl,erl}",
+        "src/*.app.src",
+        "rebar.config"
+    ]},
+    {exclude_files, [
+        "src/smtp_rfc5322_parse.erl",
+        "src/smtp_rfc5322_scan.erl",
+        "src/smtp_rfc822_parse.erl"
+    ]}
+]}.
 
-{xref_ignores,
- [
-  {smtp_rfc822_parse, return_error, 2}
- ]}.
+{xref_ignores, [
+    {smtp_rfc822_parse, return_error, 2}
+]}.
 
-{deps, [{ranch, ">= 1.8.0"},
-        {hut, "1.3.0"}]}.
+{deps, [
+    {ranch, ">= 1.8.0"},
+    {hut, "1.3.0"}
+]}.
 
-{profiles,
- [
-  {dialyzer,
-   [
-    {deps,
-     [
-      {eiconv, "1.0.0"}
-     ]
-    },
-    {dialyzer,
-     [
-      {plt_extra_apps,
-       [
-        eiconv,
-        ssl,
-        hut
-       ]
-      },
-      {warnings,
-       [error_handling,
-        unknown
-       ]}
-     ]}
-   ]},
-  {ranch_v2,
-   [{deps, [{ranch, "2.1.0"}]}]},
-  {test,
-   [
-    {cover_enabled, true},
-    {cover_print_enabled, true},
-    {deps,
-     [
-      {eiconv, "1.0.0"},
-      {proper, "1.3.0"}
-     ]}
-   ]}
- ]}.
+{profiles, [
+    {dialyzer, [
+        {deps, [
+            {eiconv, "1.0.0"}
+        ]},
+        {dialyzer, [
+            {plt_extra_apps, [
+                eiconv,
+                ssl,
+                hut
+            ]},
+            {warnings, [
+                error_handling,
+                unknown
+            ]}
+        ]}
+    ]},
+    {ranch_v2, [{deps, [{ranch, "2.1.0"}]}]},
+    {test, [
+        {cover_enabled, true},
+        {cover_print_enabled, true},
+        {deps, [
+            {eiconv, "1.0.0"},
+            {proper, "1.3.0"}
+        ]}
+    ]}
+]}.