fix for #40 - generalization of the 'deref' operator

[lutzhamel]

This PR generalizes the 'deref' operator '*' so that it can be applied to any value producing expression, e.g.:

-- pattern as value
let *(pattern x) = 3.
assert (x == 3).

-- arbitrary value expressions can become patterns
let *(1+1) = 2.

-- function calls
function goo with none do return pattern x end
let *goo() = 3
assert (x==3).

[olwmc]

Great work!! Looks fantastic. Approved!!!!