Introducing a User Preferences through a Windows-Preferences page.

Introducing a User Preferences through a Windows-Preferences page. Specifically, the current settings allow user to choose whether Domain Specifications should show Vocabulary or Shape terms. This makes it easier to introduce more settings in future.

Checklist

[x] This PR adds an entry to the CHANGELOG. _See https://keepachangelog.com/en/1.0.0/ for instructions. Minor edits are exempt.
[ ] This PR expects some manual changes to the generated code. The needed changes are detailed in the CHANGELOG entry.
[x] This PR was tested with at least one code generation, resulting in a working OSLC server.
[x] This PR does NOT break the user block code

eclipse / lyo.designer

Introducing a User Preferences through a Windows-Preferences page. #247

Checklist