New <!function> tag

[dacap]

<!function name args...>
  ...
<!end>

---

How should arguments be referenced? E.g.

<!function hello a b>
  Hello <!get a> and <!get b>
<!end>

Or

<!function hello a b>
  Hello a and b
<!end>

Which acts like the old htmlex macros. This also allows to use any text for argument names:

<!function hello $a $b>
  Hello $a and $b
<!end>

---

How should functions be called?

<!myfunc args...> or <!call myfunc args...>