increase process id range

Created by: pythoneer

Problem: The current number of possible process ids is very small and could easily lead to a reuse of those.

Solution: increase the range to usize::max_value() - 1

Changes introduced by this pull request:

CONTEXT_MAX_CONTEXTS

Drawbacks: the number pids is limited to usize maybe use u64 instead?

TODOs: nothing

Fixes: nothing

State: WIP

Blocking/related: nothing