Fix Libsass 3.3
- Bug-Reference: #34
- each iterates over lists as one-dimensional entities in libsass 3.3. This is sort-of expected behavior, since syntaxes like
@each $var1, $var2 in @list
are possible in SASS, making it unsuitable for our lax syntax. - Using a for-loop correctly parses the breakpoint-statement as lists.