Apply changes to code to support path; Add signal handling; Update README

mergeinputs.service

@@ -0,0 +1,12 @@
+[Unit]
+Description=Merge multiple keyboards into one input
+After=multi-user.target
+ConditionPathExistsGlob=/dev/input/by-path/*-kbd
+StartLimitIntervalSec=5
+StartLimitBurst=20
+
+[Service]
+ExecStart=/bin/sh -c '/usr/local/bin/mergeinputs /dev/input/by-path/*-kbd'
+
+[Install]
+WantedBy=multi-user.target