WIP: Add initial restic support.

I've added a handler and example config file for restic. Since I'll be deploying this via Ansible, I'm not intending to write a helper, etc. But, I figured I'd share what basic progress I have made.

handlers/restic.in

@@ -116,50 +116,26 @@ if [[ "$retention" == "yes" ]]; then
       fi
    fi
 
-   if [ $keep_hourly ]; then
-      if [[ $keep_hourly =~ ^[0-9]+$ ]]; then
-         debug "==> For the last $keep_hourly hours in which a snapshot was made, keep only the last snapshot for each hour."
-         keep_options="$keep_options --keep-hourly $keep_hourly"
-      else
-         fatal "If 'keep_hourly' is set, it must be an integer."
+   declare -A range_array
+   range_array['hourly']="hour"
+   range_array['daily']="day"
+   range_array['weekly']="week"
+   range_array['monthly']="month"
+   range_array['yearly']="year"
+
+   for range in "${!range_array[@]}" ; do
+      keep_range="keep_${range}"
+      keep_unit="${range_array[$range]}"
+      if [ "${!keep_range}" ]; then
+         if [[ "${!keep_range}" =~ ^[0-9]+$ ]]; then
+            debug "==> For the last ${!keep_range} ${keep_unit}s in which a snapshot was made, keep only the last snapshot for each ${keep_unit}."
+            keep_options="$keep_options --keep-$range ${!keep_range}"
+         else
+            fatal "If 'keep_$range' is set, it must be an integer."
+         fi
       fi
-   fi
 
-   if [ $keep_daily ]; then
-      if [[ $keep_daily =~ ^[0-9]+$ ]]; then
-         debug "==> For the last $keep_daily days which have one or more snapshots, only keep the last one for that day."
-         keep_options="$keep_options --keep-daily $keep_daily"
-      else
-         fatal "If 'keep_daily' is set, it must be an integer."
-      fi
-   fi
-
-   if [ $keep_weekly ]; then
-      if [[ $keep_weekly =~ ^[0-9]+$ ]]; then
-         debug "==> For the last $keep_weekly weeks which have one or more snapshots, only keep the last one for that week."
-         keep_options="$keep_options --keep-weekly $keep_weekly"
-      else
-         fatal "If 'keep_weekly' is set, it must be an integer."
-      fi
-   fi
-
-   if [ $keep_monthly ]; then
-      if [[ $keep_monthly =~ ^[0-9]+$ ]]; then
-         debug "==> For the last $keep_monthly months which have one or more snapshots, only keep the last one for that month."
-         keep_options="$keep_options --keep-monthly $keep_monthly"
-      else
-         fatal "If 'keep_monthly' is set, it must be an integer."
-      fi
-   fi
-
-   if [ $keep_yearly ]; then
-      if [[ $keep_yearly =~ ^[0-9]+$ ]]; then
-         debug "==> For the last $keep_yearly years which have one or more snapshots, only keep the last one for that year."
-         keep_options="$keep_options --keep-yearly $keep_yearly"
-      else
-         fatal "If 'keep_yearly' is set, it must be an integer."
-      fi
-   fi
+   done
 
    if [ $keep_tag ]; then
       for tag in $keep_tag