[Build] Not LESS 4 compatible

[arichiardi]

Bug Report

This is a problem I detected when upgrading Less to version 4 and therefor this belongs to https://github.com/fomantic/Fomantic-UI-LESS

I have discovered that Less 4 adds new math-related options (less/less.js#3274) and enforces parenthesis for division (less/less.js@58c89ee).

This breaks compilation, see below.

Steps to reproduce

1. Bump Less to version 4
2. Compile Fomantic-UI-LESS

Expected result

Successful compilation.

Actual result

The output is:

[lessc] - ArgumentError: Error evaluating function `unit`: the first argument to unit must be a number. Have you forgotten parenthesis? in /home/kapitan/.boot/cache/tmp/home/kapitan/git/ar-website/8lt/cz07er/css/themes/default/globals/site.variables on line 653, column 20:
652 @largeRaw        : unit( round(@largeSize * @emSize) / @emSize );
653 @bigRaw          : unit( round(@bigSize * @emSize) / @emSize );
654 @hugeRaw         : unit( round(@hugeSize * @emSize) / @emSize );

Version

2.8.7

[lubber-de]

Thanks for the bug report. It's fixed by #1819.

[arichiardi]

Well thank you for the patch!