Get rid of contribution financial type

This is a placeholder for now because I don't know of anyone yet who's interested in funding this, but it's a serious issue.

When users set a financial type for a price field or option, they're given the impression that they'll find contributions with that line item when they search or report on that financial type. This is not the case.

For example, you might have two price fields for the Fall Fundraiser Dinner: one for the event fee itself, and one for additional donations. The event fee will have the financial type "Event Fee" and the donations will have the financial type "Donation". The event requires you to pick a financial type, and you choose "Event Fee". When people make a donation along with their registration, those contributions will not appear in searches or most reports when you filter by the Donation financial type.

This is a very common scenario, and the biggest problem is that there's a bit of an empty promise made. If you do all your events through Eventbrite and ask for donations there, you aren't surprised that the donations are mixed in with the event fees. By having the same financial types available on the line items as are filters on the reports and search, the implication is that they're referring to the same data. Users are surprised that they aren't.

(This may have been a mistake in CRM-9306. If contribution types were one thing for fundraising staff to filter with and financial types were another thing for accounting staff to import, there would be no confusion, but that barn door has been open for years.)

I think the solution to this is to have search and reports use the financial_type from civicrm_line_item in addition to or instead of civicrm_contribution. Sanjay suggested that there may not actually be any purpose for the financial type on the contribution record, since every contribution nowadays has a line item. Either each line item has the same financial type as the contribution, making the contribution's financial type redundant, or it differs, resulting in the problem described above.

If there's no purpose to the financial type of the contribution, it should be removed or at least turned into just the "default" financial type for the contribution's line items.

All filters for financial type should refer to the line items, and listings of contributions should show the constituent line items' financial types.

This is a fairly big change, but it would resolve a big area of frustration and needless complexity.

(See also CRM-13683)