add a script for sourcing the timestamps from gits

Fixes #2

scripts/source-timestamps.sh

@@ -0,0 +1,28 @@
+#!/bin/sh
+
+# change this with environment
+DEFAULT_NOT_SOURCE_REGEX="/\\/assets\\//"
+NOT_SOURCE_REGEX="${NOT_SOURCE_REGEX:-$DEFAULT_NOT_SOURCE_REGEX}"
+TIMESTAMP_SUFFIX="${SUFFIX:-.timestamp}"
+LOGFILE="${LOGFILE:-/dev/null}"
+
+[ -z "$1" ] && echo "$0: no inputs specified?" >/dev/stderr
+
+while [ -n "$1" ]
+do
+	echo "sourcing directory '$1' ..." >> "$LOGFILE"
+	find "$1" -type f -name '*.md' | grep -v "$NOT_SOURCE_REGEX" | while read file ; do
+		fn=`basename "$file"`
+		dir=`dirname "$file"`
+		tsfn="$fn.timestamp"
+		(
+			echo "making timestamp in '$dir' for file '$fn' ..." >> "$LOGFILE"
+			cd "$dir"
+			if [ -f "$tsfn" ]
+			then echo "... but it already exists; skipping!" >> "$LOGFILE"
+			else git log -n 1 --pretty=format:%cs -- "$fn" > "$tsfn"
+			fi
+		)
+	done
+	shift
+done