Add new code templates to F# in XS

Current templates: ``agent``, ``outlet``, ``action``, ``du``, ``interface``, ``unchecked``, ``check``, ``virt``, ``abstract``, ``abstractp``, ``seq``, ``list``, ``array``, ``struct``, ``if``, ``elif``, ``ifelse``, ``while``, ``fort``, ``fordt``, ``fori``, ``match``, ``fun``, ``main``, ``tomap``