Consider updating to Perl 5.10

[petdance]

Is there any interest in bumping up the minimum Perl for TT to 5.10.1 which came out in 2009?

There are many places we could use defined-or for simplicity and speed. For example, Template::VMethods::list_join would go from

join(defined $joint ? $joint : ' ',
    map { defined $_ ? $_ : '' } @$list);

to

join($joint//'', map { $_//'' } @$list);

There are probably places we could take advantage of state as well. Probably less so with say.