Some indentation and highlighting features

* No automatic line wrapping (textwidth = 0)
* Intend let if last line was fun
* Fix indent after functional pattern matching
* Fix indent of case/handle patterns
* Fix indent of then/else/end in insert mode and while =
* Fix highlight of =>, :=, ...
* Highlight record fields

There is also separate plugin only for indentation & syntax features: cypok/vim-sml.