Add PHP requirement to plugin info retrieved trough API call

[petervanderdoes]

Setup:
Add a field to the header of the readme.txt
Example:
Requires at least PHP: 5.2

Use this field in the back end, to be returned when calling:
wp_remote_post('​http://api.wordpress.org/plugins/update-check/1.0/', $options);
adding it to the transient 'update_plugins'.

Then when a plug-in upgrade is available and the plugin changed to require PHP5 with in the core the option to upgrade could be disabled with some info that the PHP version X is required and the server runs PHP version Y.

Using a check during the on activation hook means that during an upgrade of the plugin the old version is already removed and the user would have to download and install the previous version of the plugin.

The patch required in teh core. the $r->required_php is made up of course.

The patch is created on WordPress 2.9.2 BTW

+1, I think this would be a great idea. helps give people a better user experience overall, in my opinion

Related: #13699

This is going to be less relevant come 3.2 and PHP 5.2.

Related/duplicate: #23880

Duplicate of #23880.