Some minor improvements

[sailingKieler]

Some minor improvements, mainly for developing.

@NiklasRentzCAU, @soerendomroes, @a-sr would that cause any issues for you?

[NiklasRentzCAU]

I do not know much about the Eclipse UI stuff, so I cannot say much about that. The additional optional dependency of kgraph.text to the klighd base package also includes the transitive dependency to the swt stuff is not as nice, but given the structure of the project it is fine I guess, no objections.

[NiklasRentzCAU]

@sailingKieler Turns out, I now do have an objection about one of the changes here, specifically with the commit 286bdab: The changes in KGraphResource break KGraphs with the "de.cau.cs.kieler.kgraphsynthesis.defaults" set. As an example, this model will not synthesize with defaults on, although they are set to "As in Model" in the synthesis:

properties: 
  de.cau.cs.kieler.kgraphsynthesis.defaults=true

knode n

For a quick fix I already tried just adding this property back in in the file, however that did not fix the problem. Reverting the commit fixed it for me again.
Can you please elaborate what the changes in that commit do and do you have an idea how we might fix the issue again with your modification without just reverting the commit?