User experience on the viewpoint tab

[benel]

For now, the viewpoint tab is split up in three incoherent edition spaces:

• the keyword panel (for tagging an entire document with a topic),
• the analysis category panel (for creating, renaming, removing a topic, displaying fragments related to a topic, removing a fragment, or moving a fragment from a topic to another one),
• the viewpoint window (opened on clicking + next to "keyword") for creating, deleting, moving a topic, but also to tag the entire document with a topic.

The idea would be to replace this with only two modes:

• a simplified mode with only what is related to the document,
• a complete mode with all that could be used on this document.

Both could be used for edition, both could be used for topics on a complete document (a.k.a. "keywords"), topics on a fragment (a.k.a. "analysis categories").

[benel]

Advanced viewpoint edition removed in v3. Use Porphyry instead.