This changeset fixes up some loading issues of dt6 and building a clean analysis/overlay structure. The analysis structure is now made by mlrMakeAnalysis, which acts as a wrapper around isanalysis and isoverlay to make them easier to use (something like mrDispOverlay). This changeset also fixes a few bugs in displaying multi surfaces (one had to do with a bad sliceIndex on a surface). ALso, RGB overlay is converted into a indexed image - the trick there was that the colormap (for now) has to be 256 colors - can't be more or less. This seems to be due to the function rescale2rgb makes some assumptions - but did not fix since there also seems to be issues with the colorbar presentation and not sure how much assumes a 256 table. Also, computeOverlay and maskOverlay could use some comments - things are pretty complicated in there.