Memory allocations

Functions related to contact handling are allocating a lot of memory.
Could be tracked down and reduced for improved speed.
The following code could be used for profiling (https://docs.julialang.org/en/v1/manual/profile/#Line-by-Line-Allocation-Tracking):
```julia
using Dojo
using DojoEnvironments

mechanism = get_mechanism(:block) 
storage = simulate!(mechanism, 1, record=true)
```