Merge branch 'screencast'

Some refactorings and enhancements to the screencast script, to allow
for advanced command-line usage.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Reconstruct Reader: Set nonlinear transforms to identity
Fiji Archipelago: UI Fixes
Weka Segmentation: Added setTrainHeader(Instances newHeader) to WekaSegmentation
Fiji Archipelago: Better error reporting, Duplex class, some simplifications
Archipelago Plugins: Clusterized 2D Batch Weka Segmentation