Incrementally improved log handling in edge_dump.sh, recover_edge.sh, and
recreate_offline_db.sh, to use the mechanism pioneered in ccheck.sh.
This is a precursor to a coming standardation of log handling in SDP.
As before, each script creates a log in $LOGS named <script_log>.<timestamp>.log.
With this change, symlinks in the LOGS directory are created so that
<script_log>.log (.e. sans the timestamp) points to the timestampped log
file.
So $LOGS/recover_edge.log points to $LOGS/recover_edge.<most_recent_timestamp>.log.
Each run of the script creates a new timestamped log, and updates the symlink
very early in proccessing.
This change is better for users and also simplifies automated
testing.