Add ability to merge two journals into one

[refactorsaurusrex]

Let's say you have two journal locations. Maybe on two separate computers. And you want to merge all the entries from one computer into the other computer's journal. It doesn't even need to be two separate machines; it can just be two separate locations on the same computer. Either way, need to add a function like Merge-Journals -From <origin_journal> -To <destination_journal to combine the entries. All empty directories on the <origin_journal> should be remove and the change should be logged in the git history.