Fix #710 - Show hlint suggestions as info items, and include end line and column numbers

ale_linters/haskell/hlint.vim

@@ -2,17 +2,30 @@
 " Description: hlint for Haskell files
 
 function! ale_linters#haskell#hlint#Handle(buffer, lines) abort
+    if empty(a:lines)
+        return []
+    endif
+
     let l:errors = json_decode(join(a:lines, ''))
 
     let l:output = []
 
     for l:error in l:errors
+        if l:error.severity ==# 'Error'
+            let l:type = 'E'
+        elseif l:error.severity ==# 'Suggestion'
+            let l:type = 'I'
+        else
+            let l:type = 'W'
+        endif
+
         call add(l:output, {
-        \   'bufnr': a:buffer,
-        \   'lnum': l:error.startLine + 0,
-        \   'col': l:error.startColumn + 0,
+        \   'lnum': str2nr(l:error.startLine),
+        \   'col': str2nr(l:error.startColumn),
+        \   'end_lnum': str2nr(l:error.endLine),
+        \   'end_col': str2nr(l:error.endColumn),
         \   'text': l:error.severity . ': ' . l:error.hint . '. Found: ' . l:error.from . ' Why not: ' . l:error.to,
-        \   'type': l:error.severity ==# 'Error' ? 'E' : 'W',
+        \   'type': l:type,
         \})
     endfor