#3 highlight-current-line-on has poor contrast

highlight-current-line-set-bg-color to black looks better. I'll muck with it later.

The vimdiff colours in the terminal look bad also.

Of course I should have used global-hl-line-mode for the emacs theme. I will look into the vimdiff again later.

I should have used the evening theme for when diff in vim. I'll add a comment in the readme about some of this.