Restructured and split into separate classes

- New LDAPSession class, containing LDAP methods
- LDAPman class renamed myShellac - Shellac-only methods
- All config and options stuff moved to 'top-level'
- Tidied up get_conf()
- myShellac supports cmdloop() and onecmd() calls (depending on cmd-line args)
- Temporarily commented-out completer decorators (bduncan to resolve)