Add script to generate checkpoint data

contrib/checkpoints.pl

@@ -0,0 +1,19 @@
+#!/usr/bin/perl
+use warnings;
+use strict;
+# Generate checkpoint data for use in src/main.cpp
+
+my $hush    = "./src/hush-cli";
+my $gethash = "$hush getblockhash";
+my $stride  = shift || 1000;
+my $count   = 0;
+my $blocks  = qx{$hush getblockcount};
+
+while (1) {
+	$count++;
+	my $block = $stride*$count;
+	last if ($block > $blocks);
+	my $blockhash = qx{$gethash $block};
+	chomp $blockhash;
+	print qq{($block,     uint256S("0x$blockhash"))\n};
+}