Add grouping options for contribution thank you letters

Currently when creating Contribution thank you letters, the grouping options only allows for listing of the financial data horizontally. Either with a or a comma. This would cause date to run off the page.

I suggest adding a couple of options to allow a user to list the contribution data vertically. It allows for unlimited items to be displayed rather than be limited to 8.5in of space and it allows for the contribution amount, date, payment instrument and check number to align side by side.

I've submitted a pull request #8804