add scatterplot analysis

This currently demonstrates how well colormaps fare when perceptual distance should
align to ditance on the map. Other measures welcome.
Merge pull request #4 from simonthum/master

add scatterplot analysis
Fixed CheckStyle errors
Fix display of BibTeX entries
Added Steiger2014 colormap
Added first attempt for JND view
Voronoi images
Cleaned up jnd view
Add voronoi computation
Added isoline view
Updated ColorSpace
Added caching for color maps
Defer updating jnd panel
Merge branch 'master' into voronoi

Conflicts:
	src/main/java/main/JndViewPanel.java
mark less relevant dots red

The only thing that is actually sensible is that below jnd 1
it does not really matter. The other cases should not play a role
in practice.
un-distort scatterplot

because the length was not evenly distributed. This is hard to avoid completely
but it should no longer be significant or noticeable now.
add the Teuling et al colormaps

Some problems concerning reproducibility may be found in the description of the maps.
I did not add a colorspace enum this time as I did not see the benefit, maybe remove it?
add median-based lines to analysis view
Bilinear interpolation
Reorganized cached color maps