Optimize bash solution for day 2.

Now loops less (only n(n-1) / 2 times instead of n^2), doesn't call echo
spuriously, and doesn't use tail/head anymore. Results in 75% less
runtime, so I'll take it.

2017/day-02/solution.sh

@@ -4,13 +4,13 @@ sum1=0
 sum2=0
 
 while read -r line; do
-	sorted=$(echo "$line" | xargs -n 1 echo | sort -n)
-	((sum1 += $(echo "$sorted" | tail -n 1) - $(echo "$sorted" | head -n 1)))
+	sorted=$(tr '\t' '\n' <<< "$line" | sort -n)
+	((sum1 += ${sorted##*$'\n'} - ${sorted%%$'\n'*}))
 
 	for a in $sorted; do
 		for b in $sorted; do
 			if [[ $a -le $b ]]; then
-				continue
+				break
 			fi
 
 			if [[ $((a % b)) -eq 0 ]]; then