wx.App object for complex reasons

necessary if the first call came before a wx.App had been created.

currently dirname has to be output as the first line, as loadLabelFile will
crash on files which don't have it.

labels which correspond to 'signal'.

classification-related stuff from MelodicImage. Renamed MelodicClassification
to VolumeLabel - intent is that it will be usable with non-melodic images.

melodicanalysis functions - .gica suffix no longer recognised.

lock up (as thousands of TaskThreads were being created, and not destroyed)

gzip image.

block until queue is empty. ImageWrapper has method to access TaskThread. This
is primarily used for testing threaded access to ImageWrapper.

for featimage module finished.

directory.