Remove "pfand" plugin

Originally written as a proof of concept demo. Reportedly it's broken
and cumbersome to use anyway, because of the external config file.

I don't think anyone is actually using this right now.

plugins/pfand

@@ -1,56 +0,0 @@
-#!perl
-
-HELP "pfand" => "Pfand zurueck";
-
-# This is a demo plugin. It's called "pfand" because "deposit" would be
-# confusing and only the Germans are crazy enough to have deposits on small
-# bottles anyway ;)
-#
-# ^^ aged like milk - the netherlands has deposits on small bottles now.
-# (but we're allowed to sell them without, for immediate consumption)
-
-# The file format for 'revbank.pfand' is simply two whitespace separated
-# columns: product id and pfand amount.
-
-sub _read_pfand() {
-    return {
-        map { split " " } grep /\S/, grep !/^\s*#/, slurp 'revbank.pfand'
-    };
-}
-
-sub command :Tab(pfand) ($self, $cart, $command, @) {
-    return NEXT if $command ne 'pfand';
-
-    return "Pfand zurueck fuer", \&product;
-}
-
-sub product :Tab(&tab) ($self, $cart, $product, @) {
-    my $pfand = parse_amount(_read_pfand->{ $product })
-        or return REJECT, "Invalid pfand amount for $product";
-
-    if ($pfand) {
-        $cart
-            ->add(+$pfand, "Pfand zurueck", { is_return => 1 })
-            ->add_contra("-pfand", -$pfand, "Pfand fuer \$you");
-    } else {
-        say "$product: Kein Pfand";
-    }
-    return ACCEPT;
-}
-
-sub tab {
-    return keys %{ _read_pfand() };
-}
-
-sub hook_add_entry ($class, $cart, $entry, @) {
-    return if $entry->has_attribute('is_return');
-    return if not $entry->has_attribute('product_id');
-
-    my $pfand = _read_pfand->{ $entry->attribute('product_id') } or return;
-
-    $cart
-        ->add(-$pfand, "Pfand", { is_pfand => 1 })
-        ->add_contra("-pfand", +$pfand, "Pfand von \$you");
-
-    return;
-}

revbank.plugins

@@ -13,7 +13,6 @@ give
 grandtotal
 take
 split
-#pfand      # makes little sense in a self service environment
 #cash       # cash tracking also requires deposit_methods to make sense
 #skim       # cash tracking also requires deposit_methods to make sense
 stock