fall early when default server config is incomplete

when /nfs/WWWdev/SANGER_docs/data/otter goes Away,
 don't try to use it
directory purpose

as I remember it from a recent team meeting
Otter/Error.pm: sub Tk::Error(): log the messages before showing the dialog (RT #317967).
hiding from 'webpublish'
added AUTHOR POD section to permit webpublishing
Otter/Debug.pm: add.
otterlace: use $ENV{'OTTER_DEBUG'}
Lace/Client.pm: use Bio::Otter::Debug .
Lace/AceDatabase.pm: use Bio::Otter::Debug .
Otter/ZMap.pm: use Bio::Otter::Debug .
ZMap/Core.pm: sub zmap_command(): create by refactoring.
Otter/ZMap.pm: sub zmap_command(): implement a valgrind debug key.
honour OTTER_DEBUG in all client scripts
B:O:L:Defaults : read+weed

hide symbols from file scope;
remove old unused
  prebinpath (now ZMAP_BIN in otterlace_env.sh)
  $start;
mark the part of the interface used by B:O:L:C
  above that is public, but not methods, and some not public;
update POD list of where config comes from
delete obsolete upgrader
B:O:L:D says config can be in $OTTER_HOME/otter_config
minor doc update for host:port --> url

(8dae54f500cf39c9f1bd738933e74d9821ae5d2c)
preparation for switch from ~/.otter_config to ~/.otter/config

any scheme to do it now seems likely to create needless problems,
 so be ready to do it later
B:O:L:Client: use get_config.
Remove redundnant server scripts, now get_config is in service.