Deprecate initial_value="variable" in 2.1

[MichaelClerx]

After discussion in #56 I think we decided to deprecate it but then forgot?

Either way, I'd like it officially discouraged starting from 2.1 :D

[kerimoyle]

I've reread this thread again and I still don't quite understand how to best construct a model without it. Here is my model:

Component which does the stuff (deep somewhere inside an encapsulation):

x = dx/dt
x(t=0) = x0 <- equivalent variable to one at the top level??

or

x = dx/dt
x(t=0) = 1 <- hardcoded deep inside the model??

How do I keep parameters/initial values separate from the model mathematics if I can't set the initial value to a variable?

[MichaelClerx]

component_deep_within
    var x interface="whatever"
    maths
        dx/dt = f(...)

component_with_all_the_initial_values
    var x interface="..." initial_value ="1"

connection:
     x to x