Introduce WP_MAX_MEMORY_LIMIT constant for the high memory limit we set when image processing and unzipping.

Ensure it is always filterable by plugins as well as configurable in wp-config
Fixes #13847 props hakre


git-svn-id: http://svn.automattic.com/wordpress/trunk@17749 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/default-constants.php

@@ -24,6 +24,10 @@ function wp_initial_constants( ) {
 		}
 	}
 
+	if ( ! defined( 'WP_MAX_MEMORY_LIMIT' ) ) {
+		define( 'WP_MAX_MEMORY_LIMIT', '256M' );
+	}
+
 	/**
 	 * The $blog_id global, which you can change in the config allows you to create a simple
 	 * multiple blog installation using just one WordPress and changing $blog_id around.