#639 new argument expansion {**}$args like python **args

[Serg G. Brester]

New argument expansion {**}$args like python **args, to call procedures with expanded named arguments...
%
proc test {{a "A"} {b "B"} {c "C"}} {
puts "- $a - $b - $c -"
}
% test
- A - B - C -
% test {**}{c Z a X}
- X - B - Z -