Add support for arrays of constants

[eyck]

CoreDSL shall support arrays of constants ether as:
const unsigned int arr[] = {3,4,5};
which inferes the size or
const unsigned int arr[3] = {3,4,5};
where size has to be specified explicitly.

[AtomCrafty]

Question: do we need to be able to evaluate arr[1] as a constant expression as well?

const unsigned int arr[] = {16, 32, 64};
unsigned int XLEN = arr[1];

[eyck]

For the usecases I have in mind: no. Does the frontend support

const unsigned int c = 32;
unsigned int XLEN = c;

[AtomCrafty]

It does, yes. I'm specifically asking about the array accesses.

[AtomCrafty]

Another question: Should this support multi-dimensional arrays with nested array initializers?

const int a[][] = { {1, 2}, {3, 4} };

[eyck]

I guess in the long run we need to, I can imagine there are algorithms which need this. So we should start with a 1-dimensional array documenting the limitation.