Revert UpdateCopyright script, as its more likely to be used post-new-year next year.

Change-Id: I980e6f7e76867d7763faae73d431cad0568a3ebd
Reviewed-on: http://gerrit.dmdirc.com/1729
Reviewed-by: Chris Smith <chris@dmdirc.com>
Automatic-Compile: DMDirc Local Commits <dmdirc@googlemail.com>

UpdateCopyright.sh

@@ -2,8 +2,8 @@
 # Update Copyright headers in all files.
 
 THISYEAR=`date +%Y`
-OLD="2006-"${THISYEAR}
-NEW="2006-"$((${THISYEAR} + 1))
+OLD="2006-"$((${THISYEAR} - 1))
+NEW="2006-"${THISYEAR}
 
 grep -iRI "${OLD}" ./* | grep -v /.git/ | grep -v UpdateCopyright.sh | grep -v update.sh | awk -F: '{print "echo \"Updating \\\""$1"\\\"\"\nsed -i \"s/'${OLD}'/'${NEW}'/g\" \""$1"\""}' > update.sh
 sh update.sh