gui: Added user notification when Snapshot is saved
gui sparc: display mean intensity as int if number is big

allows to get a better feelling on how "big" is the number quickly.
driver tlaptfm: very beginning of new actuator

Will be (first) used for SPARC
acq mng: use overlay stream metadata to update metadata

also introduce new test case to test the update.
util img: change mergeMetadata syntax

directly update the given metadata
gui: Hide scrollbars on alignment info text
Merge branch 'master' of vpn.delmic.com:odemis
gui: Added save as dialog to menu for snapshot savign
doc: document new VA for the SEM

will be used for the coming new supported SEM hardware
also add metadata to save this information.

Delete the example simulated Ebeam because it's not used anymore and doesn't fit the new API. The SimSEM code should replace it nicely.
config: add html file to the package data
gui: Made snapshot function depending on focussed view and the presence of streams
gui: Added fine align status StaticText named lbl_fine_align
Merge branch 'master' of vpn.delmic.com:odemis
gui lens alignment: connect fine alignment button

basics are working

also update the metadata of the camera streams with the correction metadata.
acq find_overlay: change electron coordinate computation

this thing is absolutely confusing. It's not clear whether the referential should
be from the borders of the SEM FoV or the actual centers of the spots.

Testing on a static optical image of 7x7, it seems it should be the actual
centers, so that's what we now use. However it seemed to be working
previously with real images... we need more testing!

Also simplify a bit the code.