Reducing redundancy in output of the semantic grid columns system

I often have the following use case when generating semantic columns:
```
.module {
  .make-xs-column(12);
  .make-sm-column(6);
  .make-md-column(3);
}
```
Meaning I need a class that fills a variable amount of columns, depending on breakpoints.
Before this patch, the code above would generate the following CSS:
```
.module {
  position: relative;
  min-height: 1px;
  padding-left: 15px;
  padding-right: 15px;
  float: left;
  width: 100%;
  position: relative;
  min-height: 1px;
  padding-left: 15px;
  padding-right: 15px;
  position: relative;
  min-height: 1px;
  padding-left: 15px;
  padding-right: 15px;
  margin-bottom: 24px;
}

@media (min-width: 768px) {
  .module {
    float: left;
    width: 50%;
  }
}

[etc. for the other media-queries]
```
I propose to use the grid system in the following way to reduce this redundancy:
```
.module {
  .make-column();
  .make-xs-column(12);
  .make-sm-column(6);
  .make-md-column(3);
}
```
or:
```
.module {
  .make-column();
  .make-md-column(3);
}
```
This means using the make-column mixin whenever we want to define a semantic column class. In my opinion this disadvantage beats redundant output though.

Your thoughts?