Updated keywords with some missing/new items.

Adds highlighting capabilities for C++11 keywords:
- `auto`
- `constexpr`
- `decltype`
- `nullptr`
- `char16_t`
- `char32_t`
- `static_assert`

Also added in the missing keywords: `enum`, `operator`, and `delete`.
I'm not sure what the third column is meant for, maybe the disabled 'find in reference' menu item.