Features/support preselection and caption on options

[kayhadrin]

1. Add ability to make an option pre-selected from dataprovider().

   var data = [
       { label: 'Cheese', value: 'cheese', selected: true },
       { label: 'Tomatoes', value: 'tomatoes' }
   ];
   $('multiselect').multiselect('dataprovider', data);

2. Add ability to set a title attribute on the option LABEL tags (visible on hover) from the OPTION[title] attribute.

   You can do it with the raw HTML select box:

   <select id="example54" multiple="multiple">
     <option value="cheese" title="Smelly">Cheese</option>
     <option value="tomatoes" title="Handsome">Tomatoes</option>
     <option value="mozarella" title="Italian">Mozzarella</option>
   </select>

   Or you can do it with dataprovider() as follow:

   var data = [
       { label: 'Cheese', value: 'cheese', caption: 'Swiss cheese' },
       { 
         title: 'This is an optgroup title',
         children: [
           { label: 'Cheese', value: 'cheese', caption: 'Smelly' },
           { label: 'Tomatoes', value: 'tomatoes', caption: 'Handsome' }
         ]
       }
   ];
   $('multiselect').multiselect('dataprovider', data);

[davidstutz]

Just for reference: #385 does also add titles for options.

[davidstutz]

Thanks for your work!

[kayhadrin]

Cheers!