better searchtools

[andrepereiradasilva]

Summary of Changes

In sequence of #xxxx, this PR does some improvements to searchtools with the goal of removing all backend searchtools layout overrides. Also does other improvements:

1. Adds a attribute noresults to the search field in the filter fields xml. This attribute contains the language string of the no results message of th searchtools
2. Adds a attribute layout to the selector field in the filter fields xml. This attribute contains the layout where the field should be rendered (no attribute for all). This is useful for views that have 2 layouts. example modules has default layout and modal layout.
3. Adds a attribute filtermode to the selector field in the filter fields xml. This attribute has only one value selector. This is used to identify which field is the selector.
4. Now it can autodetect if the filters button "Search Tools" should exist or not.
5. Removed all the, now not needed, searchtools backend layout overrides.

As PoC i implemented, in this PR, the changes in all views that currently have a "selector":

• com_menus items view: selector menutype
• com_cache cache view: selector client_id
• com_modules modules view (default and modal layout): selector client_id
• com_languages installed view: selector client_id

Also, as PoC implemented it in:

• com_checkin checkin view
• com_modules modules view (frontend popup)

Testing Instructions

1. Test the searchtools in the several views changed in this PR. You'll notice that in this views the no results message is now blue. Test if they work properly.
2. Test some of the unchanged views to test if they still work properly.

Observations

After, and if, this is merged i will change all the other views to use this new searchtools model, by replacing something like this:

<?php echo JLayoutHelper::render('joomla.searchtools.default', array('view' => $this, 'options' => array('filterButton' => false))); ?>
<div class="clearfix"></div>
<?php if (empty($this->items)) : ?>
    <div class="alert alert-no-items">
        <?php echo JText::_('COM_CHECKIN_NO_ITEMS'); ?>
    </div>

By this (moving also the no results message to the xml file noresults="COM_CHECKIN_NO_ITEMS")

<?php echo JLayoutHelper::render('joomla.searchtools.default', array('view' => $this)); ?>