Get rid of the "trivial types restriction"

[mlange-42]

Due to storing components in type-erased byte vectors, Larecs does currently support only trivial types that don't contain any pointers and heap-allocated fields. Here is an idea how to solve that. I did this in the Julia port of Ark, Ark.jl.

There is a "component storage" for every component type C, with a type like

Vector[ Optional[Vector[C]] ]

Component storages are stored in a tuple or another collection for heterogenious (but known) types. This tuple-like type can be generated at compile-time, as components are parameters of the world. This allows us to store component instances with known type.

Archetypes don't have (type-erased) columns anymore, but just contain the list of component IDs they have, and the usual masks.

Arch. ID  Component Storages         Archetypes

           A    B    C  ...
     0    V[A]  -    -               [0]
     3    V[A] V[B]  -               [0, 1]
     2     -    -   V[C]             [2]
     4    V[A] V[B] V[C]             [0, 1, 2]
     :
     :     ^
           |
           Component storage for A

As queries are also parameterized by their component types, they can get their component storages at compile time.