[FIX]In some cases the merged XML was missing blocks or fields

[sferket]

No description provided.

[bobslee]

Hi Stefaan,
Thanks for your nice change!
Before I accept your PR, I have the following question.

Regarding the following condition, the images and annotations won't be merged ?!

if tag not in ['annotation', 'image']:

[sferket]

Bob,

Both where problematic in the past. This is the reason we took them out in the old module (the Java one).
I would prefer taking them out now (just like we did in the past) and pick the implementation of annotation and image merge up in a later stage.

[bobslee]

Allright, that seems fair enough to me (for the time being).
I created issue #16 to handle those image and annotation elements in the merge.