BCEA 2.1

We're about to release the new version of BCEA, which will contain some major changes.

1. A couple of changes in the basic code that should improve the computational speed. In general, BCEA doesn't really run into troubles because most of the computations are fairly easy. However, there are a couple of parts in which the code wasn't really optimised; Chris Jackson has suggested some small but substantial modifications $-$ for instance using ColMeans instead of apply($\cdot$,2,mean)
2. Andrea has coded a function to compute the cost-effectiveness efficiency frontier, which is kind of cool. Again, the underlying analysis is not necessarily very complicated, but the resulting graph is quite neat and it is informative and useful too.
   
3. We've polished the EVPPI functions (again, thanks to Chris who's spotted a couple of blips in the previous version).

I'll mention this changes in my talk at the workshop on "Efficient Methods for Value of Information Calculations". If all goes to plan, we'll release BCEA 2.1 by the end of this week.