#120 Dates checks for better task dependencies management

[Eduardo Cermeńo]

It may be interesting not to allow trash information in
the tasks start and end date. There are three new dP
vars to active and set the default start and end date
for the tasks. This is useful when you need to register
lots of taks but are unsure about the dates. It helps
to get nice Gantt Charts working properly.

Another improvement don't let you create a new task if
the start date is earlier than the task required end
date. This makes Gantt Charts get rid of cycles in task
dependencies.

Some bug fixes: the dP variable check_tasks_dates is
somewhere called without an s, this has been fixed.
I've moved the cache disablling code to the config.php
(in /includes). I had problems with the Galeon browser
(and Mozilla).

Todo: The error reporting messages are written directly
in the code, it would be nice if I used the translating
tool. maybe nest time...

Extra info: To add the patch just update the files
modified. You only need to delete the code that makes
SQL dates from regular ones and correct the var name
check_tasks_date.
Look carefully at the diff file attached (cache
disabling code is not included take it from here:

// Deshabilitar la cache
header ("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
//header("Expires: 0");
header ("Last-Modified: " .gmdate("D, d M Y H:i:s") .
"GMT");
header ("Cache-Control: no-cache, must-revalidate");
header ("Pragma: no-cache");

)

[Eduardo Cermeńo]

Diff file