Add bibclen fixer support

Closes #1910

autoload/ale/fix/registry.vim

@@ -17,6 +17,11 @@ let s:default_registry = {
 \       'suggested_filetypes': ['python'],
 \       'description': 'Fix PEP8 issues with autopep8.',
 \   },
+\   'bibclean': {
+\       'function': 'ale#fixers#bibclean#Fix',
+\       'suggested_filetypes': ['bib'],
+\       'description': 'Format bib files using bibclean.',
+\   },
 \   'black': {
 \       'function': 'ale#fixers#black#Fix',
 \       'suggested_filetypes': ['python'],

autoload/ale/fixers/bibclean.vim

@@ -0,0 +1,15 @@
+" Author: Horacio Sanson - https://github.com/hsanson
+" Description: Support for bibclean fixer for BibTeX files.
+
+call ale#Set('bib_bibclean_executable', 'bibclean')
+call ale#Set('bib_bibclean_options', '-align-equals')
+
+function! ale#fixers#bibclean#Fix(buffer) abort
+    let l:options = ale#Var(a:buffer, 'bib_bibclean_options')
+    let l:executable = ale#Var(a:buffer, 'bib_bibclean_executable')
+
+    return {
+    \   'command': ale#Escape(l:executable)
+    \       . ' ' . (empty(l:options) ? '' : l:options),
+    \}
+endfunction