Add 2018/burton1/try.sh, rename scripthd, ...

The scripthd is now called scripthd.sh to help GitHub/browsers with
whether or not to download or show it.

The try.sh script uses the script to show the differences between it and
prog.

The README.md file has been format/typo checked.

2018/burton1/scripthd.sh

@@ -0,0 +1,43 @@
+#!/usr/bin/env bash
+
+hd=${HD:=./prog}
+
+cat $* |
+$hd |
+awk '
+BEGIN { nodup=1; group=1 }
+nodup {
+	# suppress duplicate lines
+	if ($0 == prev) {
+		if (dots == 0)
+			printf "%04x: . . .\n", off
+		dots = off += 16
+		next
+	}
+	prev = $0
+	dots = 0
+}
+{
+	# determine the number of bytes, rest is ascii
+	nb = 16
+	if (length($0) < 48 || length($16) != 2) {
+		for (nb=1; nb<NF; ++nb)
+			if (length($nb) != 2 || $nb !~ /[0-9a-f][0-9a-f]/)
+				break
+		--nb
+	}
+}
+group {
+	sz = 35
+	hex = $1 $2 $3 $4 " " $5 $6 $7 $8 " " $9 $10 $11 $12 " " $13 $14 $15 $16
+	if (nb < 16) hex = substr(hex, 1, nb*2+nb/4)
+}
+!group {
+	sz = 47
+	hex = substr($0, 0, nb*3-1)
+}
+{
+	asc = substr($0, nb*3+1)
+	printf "%04x: %-*.*s |%-16s|\n", off, sz, sz, hex, asc
+	off += nb
+}'