InABox: Add support for /region alias for /datacentre

I always type "/region" on the first try because I've spent too much
time in the cloud so region is the natural concept in my head rather
than datacentre. So let's make the robot accomodate the human.

lib/Synergy/Reactor/InABox.pm

@@ -159,15 +159,23 @@ command box => {
 
   my %switches = map { my ($k, @rest) = @$_; $k => \@rest } @$switches;
 
+  if (!exists $switches{datacentre}) {
+    if (exists $switches{datacenter}) {
+      $switches{datacentre} = delete $switches{datacenter};
+    }
+    elsif (exists $switches{region}) {
+      $switches{datacentre} = delete $switches{region};
+    }
+  }
+
   # This should be simplified into a more generic "validate and normalize
   # switches" call. -- rjbs, 2023-10-20
+  # I've made this not more generic but more clever: We first normalize to
+  # datacentre above and then check if one of the aliases is still hanging
+  # around which means a duplicate alias was passed. -- lerlacher, 2024-07-27
   # Normalize datacentre
-  if (exists $switches{datacentre} && exists $switches{datacenter}) {
-    return await $event->error_reply("You can't use /datacentre and /datacenter at the same time!");
-  }
-
-  if (exists $switches{datacenter}) {
-    $switches{datacentre} = delete $switches{datacenter};
+  if (exists $switches{datacenter} || exists $switches{region}) {
+    return await $event->error_reply("Please pass only one of /datacenter or /datacentre or /region!");
   }
 
   for my $k (qw( version tag size datacentre )) {