Update property sort order

[DanPurdy]

Updates the property-sort-order rule to ignore non standard CSS properties to allow custom properties as described in #302

Closes #302

Looking for possible feedback on this to see if we think this check should be enabled or disabled by an option flag or whether a whitelist would be preferable to this check.

DCO 1.1 Signed-off-by: Dan Purdy danjpurdy@gmail.com

[DanPurdy]

I should also add some extra text to the documentation here.

[jgthms]

This looks great 👍
Thanks!

[DanPurdy]

Going to also add a flag to this to disable this behaviour if needs be. Some might want their 'custom' properties to be ordered.

[bgriffith]

Torn on whether default value for ignore-custom-properties should be true or false.

On one hand I feel that custom values could be miss-spelt properties and therefore should not be ignored.

On the other a default action of ignoring anything custom would offer ease of use without either side having to take further actions to get this rule working for them.

Thoughts?

[DanPurdy]

I think it should remain as false. The default sort order is alphabetical and so it would provide a consistent approach straight out of the box where as it takes a little extra configuration and reading of the documentation to understand why you may not want that and to understand why your custom or misspelt property isn't being linted.

[bgriffith]

Fair point. Let's stick with false.