Copy all loclist items returned from handlers, and set up defaults for convenience

test/test_credo_handler.vader

@@ -6,20 +6,16 @@ Execute(The credo handler should parse lines correctly):
   \   {
   \     'bufnr': 347,
   \     'lnum': 1,
-  \     'vcol': 0,
   \     'col': 4,
   \     'text': 'There is no whitespace around parentheses/brackets most of the time, but here there is.',
   \     'type': 'E',
-  \     'nr': -1,
   \   },
   \   {
   \     'bufnr': 347,
   \     'lnum': 26,
-  \     'vcol': 0,
   \     'col': 0,
   \     'text': 'If/else blocks should not have a negated condition in `if`.',
   \     'type': 'W',
-  \     'nr': -1,
   \   },
   \ ],
   \ ale_linters#elixir#credo#Handle(347, [