clean up divider logic

what does this do now besides update ```_numDividers```? It looks like it just puts ```_currentLayout``` right back to the way it was minus some spaces. I was commenting on optimizing all those regex and ```_currentLayout = _currentLayout...``` statements, but if we're just counting words and clearing spaces couldn't this be even simpler?

It does get called a lot.


Some ideas:
```
// get rid of the lines that remove spaces in brackets by adding that to the exec query
// (or if this looks costly, ignore empty array elements resulting from the split())
var result:Object = /\[\s*(.*)\s*\]\[\s*(.*)\s*\]\[\s*(.*)\s*\]/.exec(
   // all that needs to happen to the original string is remove pipes
   // (we will reconstruct '_currentLayout' based on 'result' so there's no need to assign this field new values)
    _currentLayout.replace(/\|/g,'')
);
// use split to remove extra spaces
var right:Array = result[1].split(\s+);
...
```