patron loader should accept a tab delimiter more cleanly

[roganhamby]

the patron loader will accept a delimiter from a parameter argument but it needs something like 'qq|\t|' to actually set it which is not intuitive and won't pass as is from a parameter anyway so it would be nice to have a simple way to set tab as a delimiter in the parameters, perhaps with a special case for 'tab' passed to it

[gmcharlt]

I think a special case of "tab" or "TAB" would work fine.