Smart Here-docs

Idea from anoldhacker:

```
eval <<RUBY
this_should_look(:like, :ruby).code
RUBY

run_sql <<SQL
select * from foo
SQL
```

…etc.

This much could just directly map the downcased token to `'filetype'`

Another aspect is that:

```
`cat /tmp/hihi`
```

…should be `ft=shell`
