More Journals Per Transaction

[qwacko]

Allow a "split" transaction approach to have more than two journals per transaction. Items to consider:

• [ ] Ability to "add" a journal to an existing transaction.
• [ ] How the values are updated to make sure the total is zero.
• [ ] How cloning works.
• [ ] How bulk updating works (probably for items with more than two journals then the "payee" cannot be adjusted).
• [ ] How to delete a single journal without deleting the transaction.