remove hardcoded value for parameter order in render_newsgrid()

[Jimmi08]

Motivation

Flexibility with using render_newsgrid() method
Example: need to display some news in alphabetical order

Proposed Solution

No changes in the grid menu itself, it's correct.

Problem is that from documentation there is parameter order
@param integer $parm['order'] n.news_datestamp DESC

but it is hardcoded later:
$parms['order'] = 'n.news_datestamp DESC';

It could be solved similar way as normal news:
$db_order = vartrue($params['db_order'], 'n.news_datestamp DESC');

Thanks

[CaMer0n]

@Jimmi08 This commit should fix it, but please let me know if it didn't for some reason.