RFC: Use descriptive support levels in compat page.

This removes the old (and confusing) percent values and replaces them with
a simple scheme of: unsupported, playable and completable.

A initial adaption of the compatibility page of the development version has
been done. This might need some reclassification! All the old compatibility
pages keep their percent values.

I hope that such a new system is easier for the users to understand. I am not yet sure whether the three different support levels are the best choice here though. I will shortly describe the three different levels to give a better understanding:

* unsupported: This means the game is not working at all or only very little parts are playable.

* playable: The game is playable but not completable (or it is not known whether it is completable).

* completable: The game is completable.

I am not sure whether we want some more fine grained support levels, like completable (with glitches) or completable (without glitches). The names of the levels is probably also a part where it can be improved (but I can't think of anything better...). So, this is open for discussion. (On a related matter, I was not sure what to make of the compatibility of http://scummvm.sourceforge.net/compatibility/DEV/BluesTreasureHunt/ and http://scummvm.sourceforge.net/compatibility/DEV/pjgames/ in specifc. I used "completable" for now. Of course, for now it's more important to decide what levels of support want to to capture.)

Again, the implementation is probably horrible because I'm not used to PHP and Smarty.

I look forward for any feedback/suggestions.

This is a screenshot of how it currently looks like: http://lordhoto.users.sourceforge.net/scummvm-web-compat-new-1.png