Add tint and shade functions, fixes #944

[Synchro]

No description provided.

[ricardobeat]

Maybe the shade() helper should invert the amount value, so that tint/shade are symmetric: tint(10%) and shade(10%) should result in two colors equally spaced apart.

I also don't think the default amount of 10 is needed, all the other color functions don't have defaults.

[lukeapage]

Not sure what @ricardobeat means by inverting the amount value? (or the example without colours?)

I agree that a default of 10% is a bit OTT, I'd prefer people have to be explicit about how much shading they are adding.. the only defaults are where the value can be absolute

[Synchro]

Initially I agreed about the sign of the amount, but then I realised that the direction of the change is determined by the color it's blending with - tint goes towards white, shade towards black - so it doesn't need negating.
I removed the default value processing, and that stray space.

[lukeapage]

good but don't check-in the less-1.3.0.js file...

could you revert that file and rebase it into 1 commit? I can do this if your not sure how.

[Synchro]

Sigh. I thought this would be a good learning opportunity, but I think I completely screwed that up... I did (after about 20 failed attempts):

git rebase -i 53fad4f^
(set first commit to p, others to s, except for 79d801f set to e)
git reset HEAD^1 dist/less-1.3.0.js
git checkout -- dist/less-1.3.0.js
git rebase --continue
git push origin

This all made some kind of sense until the final merge (why a merge? this should be replacing?), and I've ended up with a whole new bunch of commits that seem to have ignored the squashing and reverting of that js file. What did I do wrong?

[lukeapage]

no idea, thats what I would do.

[Synchro]

Gave up on git. I trashed that entire fork and made my changes again in a clean fork/branch/pull and now it all looks happy. See #953