Add script to estimate when a block will occur

contrib/block_time.pl

@@ -0,0 +1,23 @@
+#!/usr/bin/perl
+# Copyright 2019 The Hush developers
+# Released under the GPLv3
+use warnings;
+use strict;
+
+# Given a block time, estimate when it will happen
+my $block      = shift || die "Usage: $0 123";
+my $hush       = "./src/hush-cli";
+my $blockcount = qx{$hush getblockcount};
+
+if ($block <= $blockcount) {
+	die "That block has already happened!";
+} else {
+	my $diff    = $block - $blockcount;
+	my $minutes = $diff*2.5;
+	my $seconds = $minutes*60;
+	my $now     = time;
+	my $then    = $now + $seconds;
+	my $date    = localtime($then);
+	print "Hush Block $block will happen at roughly:\n";
+	print "$date # $then\n";
+}