Add option to chdir to a particular dir

Helpful to fight cron-related issues.

dotfiles/imapdomo/utils/imapdomo

     local Debug     # true if debugging
     local cmd       # imapfilter command
     local CfgDir    # config directory
-    local LogDir    # config directory
+    local LogDir    # directory to store logs
+    local CdTo      # change dir to this before running imapfilter
     CfgDir="$HOME/.imapdomo"
     LogDir="$HOME/.cache/imapdomo/logs"
     Debug=false
     while true; do case $1 in
+        -c) CdTo="$2"; shift 2 || usage ;;
         -d) Debug=true; SHELLFU_DEBUG=true; shift ;;
         -*) usage ;;
         *)  break ;;
     cmd=$(mkcmd)
     debug -v cmd
     bash -n <<<"$cmd" || die
+    if test -n "$CdTo";
+    then
+        cd "$CdTo" || die
+    fi
     eval "$cmd"
 }