Re-organize reviews around importance rather than function

The reviews are currently organized around functional areas (SQL, style, performance). I think that this was helpful when they were first implemented As Drupal and coder has evolved, newbies are asked to make things pass coder. I've always thought that "passing coder" just meant passing the default reviews. But even the default reviews threw some false positives (things like "use drupal_ string functions"). With the integration of code sniffer, this line is even further blurred ... which sniffs are part of the standards, which ones are mere suggestions from the community, are there any sniffs that are just suggestions from the author (things like the Drupl'Art review or coder tough love do).

So I am proposing that we re-organize the reviews into importance. I'm not sure exactly what these would be. Here is one suggestions:
* required, suggested, optional

I like the above best, but we should discuss, and might have something like ticket priorities:
* critical, major, normal, minor
* critical, important, suggested, trivial

As part of this re-organization of review rules, we'll also need to re-organize the code sniffs into sub-directories. I imagine integrating sniffs more tightly to the current reviews, such that a review can have an associated sniff directory. And thus we can implement the "critical" review using whatever rules are easiest and most accurate, sometimes those rules will be regex rules, sometime grep rules, and sometimes sniff rules.