Insight units

This PR adds getter/setter methods to the Pojos enabling clients to work with the unit objects (replaces the now deprecated methods, which just return the plain values without unit information) and adjusts the various transform...() methods in EditorUtil, ensuring that the units are converted into the right dimension (the default unit used before) prior to being processed further, respectively displayed in the client.

Test: Import an image (ideally with all of the possible metadata) and make sure Insight shows the correct values. Another interesting test would be: Import an image with metadata not in default units, e. g. exposure time was assumed to be in s; now import an image with exposure times in ms; again make sure, that Insight displays the correct value (just will be converted to s). Don't know if we have/can generate images like this (Update: @qidane has generated test images for this test case openmicroscopy/bioformats#1420 , but they won't work with Insight at the moment, as the conversion methods have not been implemented yet; task for m3)

Note: In the Pojos there is now for every old, deprecated getYYY() (which just return the value as primitive) a getYYYAsZZZ() method, where ZZZ matches the Unit returned. This sometimes leads to weird method names like LightSoureData.getPowerAsPower() but at least it makes clear, that this is the method which replaces the deprecated non-unit one.

/cc @jburel @will-moore 
What do you mean, @dominikl ?