Fix #308 - Check Dart files with dartanalyzer

doc/ale-dart.txt

@@ -0,0 +1,36 @@
+===============================================================================
+ALE Dart Integration                                         *ale-dart-options*
+
+
+===============================================================================
+dartanalyzer                                            *ale-dart-dartanalyzer*
+
+Installation
+-------------------------------------------------------------------------------
+
+Install Dart via whatever means. `dartanalyzer` will be included in the SDK.
+
+You can add the SDK to `$PATH`, as described here:
+https://www.dartlang.org/tools/sdk
+
+If you have installed Dart on Linux, you can also try the following: >
+  " Set the executable path for dartanalyzer to the absolute path to it.
+  let g:ale_dart_dartanalyzer_executable = '/usr/lib/dart/bin/dartanalyzer'
+<
+... or similarly for wherever your Dart SDK lives. This should work without
+having to modify `$PATH`.
+
+
+Options
+-------------------------------------------------------------------------------
+
+g:ale_dart_dartanalyzer_executable         *g:ale_dart_dartanalyzer_executable*
+                                           *b:ale_dart_dartanalyzer_executable*
+  Type: |String|
+  Default: `'dartanalyzer'`
+
+  This variable can be set to change the path to dartanalyzer.
+
+
+===============================================================================
+  vim:tw=78:ts=2:sts=2:sw=2:ft=help:norl:

doc/ale.txt

@@ -31,6 +31,8 @@ CONTENTS                                                         *ale-contents*
       stylelint...........................|ale-css-stylelint|
     cmake.................................|ale-cmake-options|
       cmakelint...........................|ale-cmake-cmakelint|
+    dart..................................|ale-dart-options|
+      dartanalyzer........................|ale-dart-dartanalyzer|
     erlang................................|ale-erlang-options|
       erlc................................|ale-erlang-erlc|
       syntaxerl...........................|ale-erlang-syntaxerl|
@@ -172,6 +174,7 @@ The following languages and tools are supported.
 * CSS: 'csslint', 'stylelint'
 * Cython (pyrex filetype): 'cython'
 * D: 'dmd'
+* Dart: 'dartanalyzer'
 * Dockerfile: 'hadolint'
 * Elixir: 'credo', 'dogma'
 * Elm: 'elm-make'