Add rule110.sed

`rule110.sed` is an executable sed script that calculates the next
iteration of rule 110 cellular automaton. E.g. `./rule110.sed <<<0001`
outputs `0011`.

rule110.sed

@@ -0,0 +1,21 @@
+#!/usr/bin/sed -Ef
+
+# Translate to intermediate step
+# - Lowercase means previous state was 0
+# - Uppercase means previous state was 1
+# - [Aa] means new state is 1
+# - [Bb] means new state is 0
+# - Assume edges are 0
+:a
+s/([B1])1([B1$])/\1B\2/g # 111 -> 0
+t a
+:b
+s/([B1])0([B1$])/\1a\2/g # 101 -> 1
+t b
+:c
+s/([a0^])0([B1$])/\1a\2/g # 001 -> 1
+t c
+
+# Translate to final results
+s/a/1/g
+s/B/0/g