[Scutigena-code] improved heapsort.tcl

[miguel s. <mi...@ut...>]

Attached an improved heapsort.tcl (40% faster here).

It uses lists and [lset] instead of arrays, tries to reuse the result of 
variable assignments (readability <<), and is otherwise careful about 
avoiding some internal buglets (like && being slower than nested [if]s).

Also replaced bitshift ops with multiplication - small diff, small 
runtime penalty, big improvement in readability.

Miguel