Rethink the main navigation menu

[git-afsantos]

The main navigation menu currently has 4 views: Home, Issues, Source and Runtime.

Home and Issues are essential. The former gives you an overview of the analysis results and lets you select which project you are currently looking at. The latter provides you with a global overview of all issues reported by the analysis step.

Runtime currently displays the extracted feature and architecture models. Source does not really have anything at the moment. In a previous prototype of this UI, I had it display the dependency graph of all analysed packages (a view of the system's source code, as opposed to the runtime architecture).

I am thinking that maybe Runtime should be renamed, in case that we later want to delve into actual runtime views. And perhaps Source could also be renamed, or even repurposed. Having the package graph somewhere is relatively useful, and it is probably better to have it on its own page, rather than trying to collapse both packages and architecture in the same page and switching between the two with menus.