EP: Reorganize the org's packages

Aim: This enhancement proposal is to reorganize the packages orgs surrounding reachable set computations.

(this is a draft)

Steps:

1- move set-based algorithms to SetBasedRecurrences.jl

2- split the remaining parts into packages

• MathematicalPredicates.jl (properties),
• ReachabilityBase.jl (general infrastructure like ReachSet, ReachSolution, etc.),
• HybridSystemTransformation.jl (system normalization and simplification)
• ReachabilityAnalysis.jl unification of those packages, user API (solve), finding default algorithms, handling options, discrete-post operators, transformations

3- do MathematicalSets.jl

4- do MathematicalPredicates.jl

5- better docs for reachability analysis (essential)

6- PR these packages to the general Julia registry

The rest of this wiki is about point 1.