Add scalastyle linter (#766)

* Add support for scalastyle

* Add scalastyle docs

* scalastyle support for column numbers

* off by one column

* Add tests for scalastyle command and handler

* update readme for scalastyle

* allow full scalastyle options instead of just config file

* fix indentation

* allow scalastyle config file in parent directories by a couple names.

* check for missing match args with empty

* remove echo

* use a for loop

doc/ale-scala-scalastyle.txt

@@ -0,0 +1,25 @@
+===============================================================================
+ALE Scala Integration                                       *ale-scala-options*
+
+
+===============================================================================
+scalastyle                                               *ale-scala-scalastyle*
+
+g:ale_scalastyle_config_loc                       *g:ale_scalastyle_config_loc*
+
+  Type: |String|
+  Default: `''`
+
+  A string containing the location of a global fallback config file.
+  By default, ALE will look for a config file named `scalastyle_config.xml` or
+  `scalastyle-config.xml` in the current file's directory or parent directories.
+
+g:ale_scala_scalastyle_options                 *g:ale_scala_scalastyle_options*
+
+  Type: |String|
+  Default: `''`
+
+  A string containing additional options to pass to scalastyle.
+
+===============================================================================
+  vim:tw=78:ts=2:sts=2:sw=2:ft=help:norl:

doc/ale.txt

@@ -93,6 +93,8 @@ CONTENTS                                                         *ale-contents*
       rustc...............................|ale-rust-rustc|
     sass..................................|ale-sass-options|
       stylelint...........................|ale-sass-stylelint|
+    scala.................................|ale-scala-options|
+      scalastyle..........................|ale-scala-scalastyle|
     scss..................................|ale-scss-options|
       stylelint...........................|ale-scss-stylelint|
     sh....................................|ale-sh-options|
@@ -206,7 +208,7 @@ The following languages and tools are supported.
 * Ruby: 'reek', 'rubocop'
 * SASS: 'sasslint', 'stylelint'
 * SCSS: 'sasslint', 'scsslint', 'stylelint'
-* Scala: 'scalac'
+* Scala: 'scalac', 'scalastyle'
 * Slim: 'slim-lint'
 * SML: 'smlnj'
 * Stylus: 'stylelint'