DataTable fields filter: possibility to add custom filter field

[vadjs]

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Current behavior

DataTables now have good feature - possibility to define custom element of global filter. Would be good if column filters will have feature to define custom element, like in global filter.
I think, best way will be through adding filterElement attribute.

Expected behavior

Minimal reproduction of the problem with instructions

What is the motivation / use case for changing the behavior?

Sometimes developer need to customize filter of any columns. Also sometimes developer needs to use dedicated search window. That feature will allow to use it.

[cagataycivici]

Duplicate of #196