Junction modeling

[mrp089]

We currently assume that static pressure is preserved over junctions. In the future, we would like to switch between different junction models:

• preserve total pressure (= static pressure + dynamic pressure)
• John Mynard's unified0D model
• junction pressure loss predicted by Neural Network

[mrp089]

As a first step, I'll add a new junction type that allows passing geometrical information about junctions to the 0D solver