Big changes committed in SVN

Hi all.

I committed a rather big change in trunk.

It fixes some bugs. I added some new test cases, but it is such a
fundamental change that I can not be sure nothing got broken.

I did not clean it up to be the prettiest thing. I have not much time
to work on it. I need to get it off my hands because there already is
a conflicting patch for PIC14E support.

Have fun.

Marko