Fixes lost-column too much code generation

[poxrud]

Fixes the issue #256 where lost-column generates two identical css selectors, each with it's own rule, instead of combining them into one.

For example:

.mydiv:nth-child(4n){
  float: right; }
.mydiv:nth-child(4n){
  margin-right: 0; }

Should instead be combined into:

.mydiv:nth-child(4n){
  float: right;
  margin-right: 0;
 }

[peterramsing]

Epic. Thanks!