Prepare Bootstrap for LESS 1.4.0

[gaurav21r]

The good people at (https://github.com/cloudhead/less.js) are working on version 1.4.0 for LESS.
Apparently this breaks 1.3.1 code. Bootstrap also fails to compile under 1.4.0 (dev).
Please have a look here (less/less.js#1042)
Maybe bootstrap should change to the changes in LESS convention?

[mdo]

Since there are no specifics here, and we're talking about supporting alpha/beta dependencies, I'm going to close this out. I'll reach out to the Less folks and see what we can do.

[gaurav21r]

@mdo With reference from (less/less.js#1042 (comment)) we now have a specific list of changes that we need to undertake to make Bootstrap LESS 1.4 Compatible.

Put all operations into brackets
replace

~(@{a}) {
}

or

:nth-child(@a)

with

@{a} {
}
:nth-child(@a)

Can we continue the discussion here in terms of a roadmap?