clean up filter code to work with alias prefixes

Custom filter handler are still a common problem, if one uses views fusion.
This is because they often use add_where in conjunction with $filterinfo['table'] - which isn't aliased and can't be, as modules might want use $query->ensure_table(), which needs the unaliased table.
Only views_filter_handler_default manually applies the table alias, so this is working.

So I had a look at this all and how we could clean up this mess a bit.
-> I propose to make use of $query->get_table_name($table) on all tables, before they are added with add_where(). This adds the table alias prefix, if necessary.

Attached is a patch, which cleans the most common filter handlers, as well as all others I was able to find, that make use of add_where() with their tablename. I've tested all modified filters as well the default handler to work with and without views fusion.

As an affect it fixes
* all filters using views_handler_filter_like
* all filters using views_handler_filter_timestamp
* the File: Has file downloads filter
* the Node: Current User Authored or Commented filter

to work with views fusion too.