Clicking the Wiki navigation link adds the wrong characters into the wiki link.

If the project name has a space then the Mediawiki link has a plus in it e.g. My+Project. Plus is a valid Mediawiki character so the title of the page incorrectly contains the plus as well.

Changes: core/classes/MantisCoreWikiPlugin.class.php

        function base_url( $p_project_id=null ) {
                $t_base = plugin_config_get( 'engine_url' ) . 'index.php/';
                if ( !is_null( $p_project_id ) && $p_project_id != ALL_PROJECTS ) {
                        //$t_base .= urlencode( project_get_name( $p_project_id ) ) . ':';
--->                    $t_base .= project_get_name( $p_project_id ) . ':';
                } else {
                        $t_base .= urlencode( plugin_config_get( 'root_namespace' ) );
                }
                return $t_base;
        }