Uniform distribution support for crave vairables

[voertler]

Make crave variables default uniform distributed over their value range (alignment to SystemVerilog default behavior))

[hvdschoot]

I have tested the uniform distribution fix, and see it behaving favorably in that I now indeed get random values for crave variables that do not have constraints on them. That said, I do still run into quite some issues overall, with certain constraints seemingly not working, or not being solved properly, or not being solvable by the (Z3) solver, and other such related peculiar things, too convoluted to list here. The worst is, getting a segmentation fault during the solver process appears more the rule than the exception.

I will need to find a proper yet non-laborious way of communicating these various issues, which won't be easy as my observations are all over the place and it is challenging to get my head around it. I'll have to see to what extent I can create examples of misbehavior, but I'd first rather start with a review meeting for instance with Thilo going over some of my Crave code to discuss what I am aiming to do. Extracting small non-proprietary examples out of this such that these examples also fail is ptentially a big job, which may be significantly short-cut by a review meeting first.

[SchulzSt]

VWG: related to #4

[SchulzSt]

Coseda contribution notice missing (see also CONTRIBUTORS)