Allow default values for ByRef parameters

[genius257]

Current behavior:

Func Example(ByRef $a=1)
  ;
EndFunc

Output:

"{...}.au3" (1) : ==> Badly formatted "Func" statement.:
Func Example(ByRef $a=1)
Func Example(ByRef $a^ ERROR
Exit code: 1

Ticket #3892 uses this syntax in example code, but does not necessarily seem to be directly related

[Jpm]

I confirm not related as the objectif is to pass the value with a keyword
Example(a=1)
in this case as there is no may parameter not useful

Back to your proposal when calling the variable must exist to be updated on the return
so I will leave to Jon the final answer but for me I cannot see to have it working

[Jpm]

In fact this request is the same as #3540