git meta diff should understand --word-diff

`git diff --word-diff` is very useful for figuring out change code changes when a lot of white space changes have occurred, such has re/de-indenting blocks of code.

`git meta diff --word-diff` does not error but also does not pass the argument down argument down to the individual `git diff` commands.

git meta should likely pass all arguments of after the diff to the individual `git diff`s