w2fields refactor - part1

- removed the multiple recalculation / enhancements of elements => more caching of these variables, less time spent

$(this) => $this
$(this).prev() => $this.prev() => $thisPrev
$(this).next() => $this.next() => $thisNext

- use one "var" for multiple variables

Question: What you think? If this is okay, i'll continue with the rest of this file.

 

off-topic: i dont know why the latest changes are also included in my pull request, any hints how i can stop this on future pull requests?