* Several small UI problems

* Some unused code removed

* User's entered Node Expire data for Book nodes were overwritten when saving. Its not needed anymore, since users cannot change these data

* SQL queries where redundant in order to check if a given node already had Node Expire feature data. Its now loaded only once.
* Several optimizations on hook_nodeapi(). Its now about 50% of the original size and its much faster

* The node form now adds the node expire values even if the user has no permission to modify it.

* Code organization on _node_expire_propagate_book()

* _node_expire_propagate_new() renamed to _node_expire_propagate_book() for consistency
* Move _node_expire_propagate_book() to a specific file since its not needed on every page load. It make the module lighter

* Simplify the 'insert' and 'update' operation on hook_nodeapi().

* Simplify the 'prepare' operation on hook_nodeapi().

* Check if the Node Expire feature is enabled for the given nodetype before execute any operation on hook_nodeapi().

* hook_update code to convert 'expiration_type' variable into 'expiremode'

* 'expiration_type' PHP variable renamed to 'expiremode' for consistency to the DB field

* 'expire' DB field renamed to 'expire_timefrom' for consistency to the rest of the PHP code

* hook_nodeapi()'s 'view' operation removed
* hook_nodeapi()'s 'load' operation added

* Cron functions are now placed in a specific file. Its better to remove Cron's code from .module file because it wont be needed on every single page. It reduces the module footprint (memory consumption).

* When there was no outdated node, an PHP error message was showing up

* Simplify the access for outdated nodes' list

* url() function changed the argument list on D6
* SQL statement with ambiguous fields

* hook_cron() unpublish nodes' code is somewhat optimized

* node_expire_default_settings_form() now uses system_settings_form() to manage saving and reseting variables
* node_expire_default_settings_form() validation and submit functions improved

* node_expire_settings_form() now uses system_settings_form() to manage saving and reseting variables

* Strings related to a list of periods now uses arguments for the sake of translators

* Better 'expired nodes' admin page code
* 'expired nodes' now uses theme function

* Since date functions are not standardized thru DBMS, node_expire now uses normal timestamp integers to represent dates

* Since date functions are not standardized thru DBMS, node_expire now uses normal timestamp integersto represent dates

* Code organization
* Minor performance improvements

* Use PHP's strtotime() function instead a custom-made algorithm on hook_update

* Code organization

* Code organization

* A menu item definition was wrong

* Newly created DB columns are now set as indexes too

* hook_install() now convert all DB data to the new schema
* hook_schema() changed to reflect the new "expire" value

* Correct access callback function

* Schema data was not being returned.

* Parameters to drupal_mail() have changed

* in most cases (when dealing with potential Unicode strings), replace the string function with the drupal_ equivalent string functions

* in most cases (when dealing with potential Unicode strings), replace the string function with the drupal_ equivalent string functions

* SQL query handling data in a potentially insecure way by using the %s placeholder without wrapping it in single quotes. This is a potential source of SQL injection attacks when the value can come from user data.

* Small PHP code error