closes #48: Join/Load Layout should support workspace-relative locations
fixes #50: default column suffix is mixed up with multiple normalization
nodes
fixes #47: Operetta reader - fails to read result file

result file may not contain non-numerical data, now throws understable
error message
Add to Operetta Reader description: only numerical data allowed
fixes #45: Row Splitter / Filter - incoming column spec handling
fixes issue #44: Plate Heatmap Viewer - sorting plates
Bump up version numbers
Merge branch 'release_1.4'