Add support for AVRA linting (#3950)

* Add support for AVRA linting

* Add tests for AVRA linting and improve code

* Fix test

* Fix warning detection

* Fix test

* Fix test

* Add AVRA as a supported language in docs

doc/ale-avra.txt

@@ -0,0 +1,26 @@
+===============================================================================
+ALE AVRA Integration                                         *ale-avra-options*
+
+
+===============================================================================
+avra                                                            *ale-avra-avra*
+
+g:ale_avra_avra_executable                         *g:ale_avra_avra_executable*
+                                                   *b:ale_avra_avra_executable*
+
+  Type: |String|
+  Default `'avra'`
+
+  This variable can be changed to use different executable for AVRA.
+
+
+g:ale_avra_avra_options                               *g:ale_avra_avra_options*
+                                                      *b:ale_avra_avra_options*
+  Type: |String|
+  Default: `''`
+
+  This variable can be set to pass additional options to AVRA.
+
+
+===============================================================================
+  vim:tw=78:ts=2:sts=2:sw=2:ft=help:norl:

doc/ale-supported-languages-and-tools.txt

@@ -33,6 +33,8 @@ Notes:
   * `write-good`
 * ASM
   * `gcc`
+* AVRA
+  * `avra`
 * Awk
   * `gawk`
 * Bash

doc/ale.txt

@@ -2633,6 +2633,8 @@ documented in additional help files.
     textlint..............................|ale-asciidoc-textlint|
   asm.....................................|ale-asm-options|
     gcc...................................|ale-asm-gcc|
+  avra....................................|ale-avra-options|
+    avra..................................|ale-avra-avra|
   awk.....................................|ale-awk-options|
     gawk..................................|ale-awk-gawk|
   bats....................................|ale-bats-options|