Ability to quickly switch both panels in 'compare' mode

[errael]

(This is copied from sjl/splice.vim#32)

More often I find myself switching between "one <-> result" and and "original <-> two". I am copying the changes from "Original <-> two" into "one <-> result". The diff between "original <-> result" is not very helpful as it shows too many differences. I thought it would be nice to have simple way of switching the two views.

At the moment I am using these two command lines to achieve that:

:exe 2 . "wincmd w" | call splice#SpliceOriginal() | :exe 3 . "wincmd w" | call splice#SpliceTwo()

and

:exe 2 . "wincmd w" | call splice#SpliceOne() | :exe 3 . "wincmd w" | call splice#SpliceResult()