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

test/test_standard_handler.vader

@@ -6,29 +6,23 @@ Execute(The standard handler should parse lines correctly):
   \   {
   \     'bufnr': 347,
   \     'lnum': 47,
-  \     'vcol': 0,
   \     'col': 14,
   \     'text': 'Expected indentation of 2 spaces but found 4.',
   \     'type': 'E',
-  \     'nr': -1,
   \   },
   \   {
   \     'bufnr': 347,
   \     'lnum': 56,
-  \     'vcol': 0,
   \     'col': 41,
   \     'text': 'Strings must use singlequote.',
   \     'type': 'E',
-  \     'nr': -1,
   \   },
   \   {
   \     'bufnr': 347,
   \     'lnum': 13,
-  \     'vcol': 0,
   \     'col': 3,
   \     'text': 'Parsing error: Unexpected token',
   \     'type': 'E',
-  \     'nr': -1,
   \   },
   \ ],
   \ ale_linters#javascript#standard#Handle(347, [