Docs up to date for 0.8

[PiispaH]

Here are a couple of things that were discussed in the MOPO meeting in Leuven on what to do for the documentation in preparation for 0.8.

Overall

• Formatting by General consistency in #2156
• Check that new features in 0.8-dev branch that are worth to mention in the documentation are included in there
• Images may have gone out of date (at least Tool properties and spec editor UI have changed)

Related to database editor changes

• [x] #2306
• [ ] Add section or even own page about configuring and viewing the dynamic graphs
• [x] Replace references to objects and relationships with entities everywhere in the docs:
  • getting started
  • API Reference also has some mentions of objects and relationships since some of the code still has these mentioned

Terminology

• [x] Update terms that need updating (new ones could still be added)