Add a dedicated multi-dimensional space type

[findmyway]

Ref: #257 (comment)

[albheim]

Was the Space type added after the original comment, or would that not be a way to achieve what is asked for there?

Original comment

Is a vector of ClosedIntervals really the best way to represent a multidimensional action space? Then you have rand(action_space(env)) returning a ClosedInterval. Surely that is not what we want.

I think we need a dedicated multi-dimensional space type. It is probably worth creating a package for this if it does not already exist somewhere. It would be useful for POMDPs.jl also for instance

Example

using ReinforcementLearning, IntervalSets
space = Space([1.0..2.0, 300.0..400.0])
rand(space) # [1.23874, 345.56190]

[findmyway]

I remember I added it after that.

Current implementation of Space is kind of ad-hoc, without a clear documentation. I think we still need to split it out so that other packages can benifit from it.

[findmyway]

Created a new package https://github.com/JuliaReinforcementLearning/CommonRLSpaces.jl to address it.