LibUCW: Let cf_reload() reload all configuration files.

LibUCW: Let cf_reload() reload all configuration files.

When a program is started with `-C' and/or `-S' switches to override the
default configuration and cf_reload() was called afterwards, it destroyed
the custom configuration and loaded the default instead.

To avoid this problem, I have added a list of configuration entries which
remembers all config files loaded and all configuration fragments executed,
as long as they are performed in the `postpone_commit' mode. The reloader
then re-executes all these operations and it records them in the new pool.