Add Vhl/highlight-reversed

[wavexx]

So here's some fun about issue #8.

I add a 'reverse' parameter to vhl/add-range that marks the two regions around the selection. In addition to that, I added a general 'Vhl/highlight-reversed' variable to define the general behavior of vhl/add-range, which simply flips the value of 'reverse'.

How does it look like?

This is how it normally looks after yanking a block of text:

and this is afterwards:

I've chosed "#999" here for the highlight background (yes, it's normally lighter).

I have mixed feelings... it's very nice if the region is large (>1 line), but it sucks for small yanks.
It's also incomplete: vhl/add-range should poke holes in the overlays when vhl/add-range is called repeatedly with an inverted region.

It's a funny test anyway.
Comments?

[toctan]

@wavexx This is awesome, I would really like to try it.

[wavexx]

Just clone https://github.com/wavexx/volatile-highlights.el/tree/highlight-reversed, then customize Vhl/highlight-reversed.