Ezigrade 4.0.2.186

We have been changing some internal functions recently in preparation for a complete rewrite of the grading functions. This has led to some unwanted speed issues. So if you have installed or updated within the last 3 weeks, we suggest you update to the latest. This version has some optimisations in the grading routines. Faster triangulation and contouring routines. And a couple of miscellanous bug fixs.