Remove parameter T from most all parametric types

The type `T`, used to indicate the type of numbers used, i.e. Float64, FLoat32, etc.. appear in many parametric types:

```julia
Shape{T<:AbstractFloat,Dim}
Particle{T<:AbstractFloat,Dim,P<:PhysicalMedium,S<:Shape}
```
and many more... Keeping track of `T` is pointless, as we do not dispatch based on this in any circumstance. It only currently helps enforce that a set of types all use the same `T`. Enforcing this has almost no purpose, and is at times annoying.

This `T` should be removed from almost all parametric types.