Both restrictions uses same rule name but which needs different
keyring directories. So, we need to handle carefully the context of
two restrictions.

modified to use proper log$role().
bug fix log messages if needed.

o fix comments.
o fix messages/error messages.
o use //o if could.
o specify initial value.

renamed to _apply_{old,new}_admin_command_mail_restrictions().

FML::Restriction::Command class.

modify $admin_command_mail_restrictions to switch to use them.

[*_program -> *_function]

$use_command_mail_program   -> $use_command_mail_function
$use_digest_program         -> $use_article_digest_function
$use_distribute_program	    -> $use_article_post_function
$use_error_analyzer_program -> $use_error_mail_analyzer_function

[command list]

$commands_for_user            -> $user_command_mail_allowed_commands
$commands_for_stranger        -> $anonymous_command_mail_allowed_commands
$commands_for_privileged_user -> $admin_command_mail_allowed_commands
$commands_for_admin_cgi	      -> $admin_cgi_allowed_commands

[restrictions]

$post_restrictions -> $article_post_restrictions
$post_restrictions_reject_notice_data_type
-> $article_post_restrictions_reject_notice_data_type

$command_restrictions -> $command_mail_restrictions
permit_commands_for_stranger -> permit_anonymous_command_mail

$admin_command_restrictions -> $admin_command_mail_restrictions