o finish() calls message flush sub-system.
o cgi_execute_command() is enhanced to handle both *admin.cgi and anonymous cgi case.
o some error messages are natural-languaged.
o use cgi_var_*() and specify -target if could.

fix copyright.

langinfo_XXX() e.g. langinfo_get_charset()...

get_article_id                 -> article_get_id
set_article_id                 -> article_set_id
config_files_append_to_list    -> config_files_append
append_to_config_files_list    -> config_files_append_to_list
get_config_files_list          -> config_files_get_list
load_config_files              -> config_files_load
set_config_files_list          -> config_files_set_list
verify_sender_credential       -> credential_verify_sender
get_current_process_ml_name    -> current_process_get_ml_name
set_current_process_ml_name    -> current_process_set_ml_name
fix_perl_include_path          -> env_fix_perl_include_path
parse_exception                -> exception_parse
parse_incoming_message         -> incoming_message_parse
clean_up_incoming_queue        -> incoming_message_queue_clean_up
get_cui_menu                   -> menu_get_cui_config_file_path
get_gui_menu                   -> menu_get_gui_config_file_path
resolve_ml_specific_variables  -> ml_variables_resolve
outgoing_message_open_channel  -> outgoing_message_cache_open
open_outgoing_message_channel  -> outgoing_message_open_channel
inform_reply_messages          -> reply_message_inform
prepare_file_to_return         -> reply_message_prepare_template
clean_up_tmpfiles              -> tmp_files_clean_up
reset_umask                    -> umask_reset
set_umask_as_public            -> umask_set_as_public

use Mail::Message::Date instead of `date`.
fix comments.