Named colours not translated to hex in arithmetic

[valtron]

Example:

// less

@col: pink;

#foo { background-color: @col * 0.8; }

// output css

#foo { background-color: pink 0.8; }

// expected css

#foo { background-color: #CC99A2; }

[joeldrapper]

@valtron There are also problems using darken and lighten functions with named colors. For now, you could import this http://cl.ly/11012A021g0M1W0k331m and then use variables instead of named colors. i.e. background: @red;