OpExportSlot: Don't crash if the coordinate offset is mismatched from the input shape.
OpFormattedDataExport: Minor fix: Use correct variable when checking if the subregion input has changed.
OpPixelFeaturesPresmoothed: Added getInvalidScales() function.
Slot.meta.shape must always be a tuple.  MetaDict now checks for this.
Added OpDvidVolume and support for it in OpInputDataReader.py
Added submodules directory and added dvidclient to it.
Don't choke if dvidclient isn't available.  Just proceed without OpDvidVolume
debug log statement.