[PATCH] Coloring Side-By-Side Changes

[Dabrien 'Dabe' Murphy]

Hi,

I apologize if this isn't the best way to submit patches, but I've often 
wondered why `diff -y` only colored the (red) deletions and (green) 
insertions, when it's often the `| ` side-by-side changes I want to spot 
quickly...  Maybe it's already been discussed to death, and shot down 
numerous times, but I couldn't find any specific conversations in the 
archives after the initial flurry of activity back in 2015.

Anyway, these changes are pretty trivial and superficial -- and they 
don't seem to fail any existing regression tests -- though I freely 
admit I'm not particularly knowledgeable about the inner-workings of 
`diff`; it's wholly possible that I've missed any number of edge cases.  
[I often say, "Nothing is easy; if it is, you're not thinking hard enough."]

I've broken it into two patches (attached), which can be applied in an 
either-or fashion to the current HEAD, depending on your desired level 
of customization:

- https://dabe.com/misc/diffutils--side-color.diff
-- This one simply re-uses the `ln` "Line Number" color palette / 
context, which, as far as I can tell, isn't displayed in side-by-side mode.

- https://dabe.com/misc/diffutils--side-color-yc.diff
-- This one adds a new `yc` "Side-By-Side Change" color palette / 
context, in case users want to customize it separately.  (Note: I just 
made up `yc`...  I didn't spend a LOT of time searching, but it didn't 
seem to be used in any, e.g., terminfo(5)-type documentation I could find.)

Thanks for your consideration,

--
:- Dabe

diffutils--side-color.diff
Description: Text document

diffutils--side-color-yc.diff
Description: Text document