Add static texts to generated file

[Jonas Rapp]

Add the possibility to include static texts to the generated file.
For example you might want a static file with rectangle definitions boxing entities together in the model.
That could be accomplished by either adding the line:

!include EntityBoxes.plantuml

if you have a local file defining the rectangles in the same folder, or by including the rectangles directly as static text:

rectangle Geography #LightBlue {
    entity jr_City
    entity jr_Municipality
    entity jr_County
    entity jr_PostalCode
}

rectangle Types #Silver {
    entity jr_ParentCategory
    entity jr_Category
    entity jr_Type
}

---

• Deployment: Online
• DB Version: 9.1.0.16541
• XTB Version: 1.2020.4.38
• Tool Version: 1.2020.2.1