Enhance HTML viewer

[johann-petrak]

These would be very cool to have:

• allow to limit the annotation sets / types to send over
• allow to pre-select set/type combinations for viewing
• allow to update the annotations or the document through calling some method: then sending over HTML to a notebook could already be used to show how annotations or the document changes as a process runs
• implement a change logger that does this: send annotation updates to a specific viewer with a specific ID

[johann-petrak]

Added by mistake

[joancf]

I would add: Perform highlighting upon selection of a given annotation, To do so, a palette of softer(pastel) colors may be need

[johann-petrak]

Limiting the annotation sets/types has been implemented, see parameter annspec: somedoc.show(annspec=["set1", ("set2", ["type1", "type"])]

[johann-petrak]

Preselecting annotations has been implement, see parameter preselect: somedoc.show(preselect=[("set1", ["type1", "type2"])])

[johann-petrak]

For a "live" viewer (and maybe support for interactive annotating) perhaps consider a mechanism similar to the one used for jupyter widgets, see https://ipywidgets.readthedocs.io/en/stable/examples/Widget%20Low%20Level.html