Add support for nested namespaces

[skillmaker-dev]

Proposal

I think it would be a great feature to have, nested namespaces make it easier to represent packages or namespaces in which classes reside, and it should be possible either by creating a namespace inside another namespace or by separating namespaces with a dot like this namespace example1.example2.example3 {}

Example

for example in PlantUML, nested packages or namespaces can be represented like this package foo1.foo2.foo3 { class Object }

Screenshots

The previous example will be represented in this way in plantUML: