move html from paginate functions to template

- add new `paginate.tpl` template
- add new `paginate_data(&$a, $count=null)` function wich returns data as array for template
-  `paginate()` and `alt_pager()` use `paginate_data()` and template to return html

with this is possible also to insert pagination in page without append it to output string in view function:
```php
function mymod_content(&$a){

   $pager = paginate_data($a);

   $tpl = get_markup_template('mymod.tpl');
   return replace_macros($tpl, array(
        'pager' => $pager
   ));
}
```
(in mymod.tpl : )
```tpl
<h1>MyMod</h1>
{{include "paginator.tpl"}}

<p>Look Ma! Paginator on top!</p>
```