Do not check for the type of certain instances but use try-except to check for attributes. Was broken due to datasource decorator. Fixes #342
implement cache memory usage dialog and status bar
opening a project can take some time: show wait cursor, status msg
remove dead code
restoreOverrideCursor() is the correct usage

...otherwise, none but the arrow cursor would be shown
subsequently
debug: time the project loading
bad objects warning dialog works. fixes #343.
object extraction returns features in a nested dictionary.

object extraction serializer works with new features format.
object workflow uses logging instead of print statements
applet serializer uses logging
fix the object extraction test
Added a feature selection dialog to the object classification gui.

closes issue #275.
correct the first 2 tests of object classification
fix all object classification tests
renamed feature slots to make them more obvious
cleaning up object extraction tests
adapted object extraction tests to new feature data structure.
comments to explain the feature slot nested dictionaries.
cache memory dialog handles exception if operator does not support report generation
remove synapse workflows from startup, put object prediction workflow there