Bug fixes and batch compatible methods

Bug fix

• fix parent table size bug. When multiple tables (at image level) were merged together in a parent table, it crashes if the number of columns were different. This is now corrected and it allows merging tables with different number of columns
• fix wrong rgb/fluo conversion. Brightfield images coming from a Zeiss slide-scanner were considered as fluorescence images. This bug is fixed by removing the condition on the image format (previously restricted to .vsi files)

Enhancement

• Adapt the 'sending to omero' and 'copying from omero' methods to be batch compatible, mainly by removing the call to QP.getCurrentViewer()
• Turn the 'fetch thumbnail exception' to debug, so that it doesn't appear by default in the log window but still keeping track of it.