oceani: remove the need for 'then' in function declarations.

oceani: remove the need for 'then' in function declarations.

Previously an IN had to follow a terminal because it would never for a
reduce.
This made is a problem for
    func FuncName
          arguments
    do
          code

as the IN follows FuncName - a non-terminal.

Fix this by allowing an IN to force a reduce if nothing at all can be
shifted.
After "func IDENTIFIER", nothing can be shifted.  The IDENTIFIER must be
reduced to FuncName.  At that point, the IN is expected, so it won't be
ignored.

This allows the 'then' to be dropped.

Signed-off-by: NeilBrown <neil@brown.name>