Fix future namespace issues for functions taking $var_to_set -- functions

Fix future namespace issues for functions taking $var_to_set -- functions
taking a variable to set need to make sure they protect their locals; if
$var_to_set positional argument coincides with a local the expected call
to `setvar' will fail to reach outside of the function's namespace. When
such collisions are experienced (as I did in the rewrite of usermgmt) the
solution is to append a full or abbreviated version of the function name
to the local (ultimately eliminating collisions). This is rarely needed
and only occurs when you have a lot of like-named functions that pass
very similar $var_to_set positional arguments to each other (such as-is
the case with an expansive library such as `dialog.subr').