added searchfield option to implement search box searching of data

This is an implementation of search box functionalty that I'm using, it adds the field `searchfields` to the tabular options for example:
```javascript
...
collection: Messages,
searchfields: ["sender", "receiver"],
order: [[ 8, "desc"]],
...
```
And then data entered into the search box is added as an `$or` selector on `$regex` to the client->server query like this:
```javascript
{$or: [{"sender": {$regex: search}}, {"receiver": {$regex: search}}]}
```
Where `search` is the string from the search box.
It does change/break the `selector` functionality as it overrides this when there is data in the search box otherwise it falls back to the `selector` or `{}`.