CSSLinter not working with latest SublimeLinter update
I've updated CSSLinter to latest 1.0.5 and restarted Sublime text a few times after SublimeLinter update, but the error still appears.

```
SublimeLinter: #133 csslint styleold.css ERROR:

 Linter crashed.

Traceback (most recent call last):
  File "lint.backend in C:\\Users\\Lee\\AppData\\Roaming\\Sublime Text 3\\Installed Packages\\SublimeLinter.sublime-package", line 97, in execute_lint_task
  File "lint.linter in C:\\Users\\Lee\\AppData\\Roaming\\Sublime Text 3\\Installed Packages\\SublimeLinter.sublime-package", line 813, in lint
  File "lint.linter in C:\\Users\\Lee\\AppData\\Roaming\\Sublime Text 3\\Installed Packages\\SublimeLinter.sublime-package", line 847, in find_errors
  File "linter in C:\\Users\\Lee\\AppData\\Roaming\\Sublime Text 3\\Installed Packages\\SublimeLinter-csslint.sublime-package", line 57, in split_match
TypeError: 'NoneType' object is not iterable
diff --git a/lint/linter.py b/lint/linter.py
index 041a856..14e3822 100644
--- a/lint/linter.py
+++ b/lint/linter.py
@@ -872,8 +872,10 @@ class Linter(metaclass=LinterMeta):
         if line:
             match_dict["line"] = int(line) - self.line_col_base[0]
         else:
-            logger.info("'line' is not optional. {}".format(match_dict))
-            return None  # log but do not err for now
+            # `line` is not optional, but if a user implements `split_match`
+            # and calls `super` first, she has still the chance to fill in
+            # a value on her own.
+            match_dict["line"] = None
 
         col = match_dict["col"]
         if col:
['lint/linter.py']