[arellano] get rid of jitclass (#131)

* [arellano] use namedtuple

* further_edits

* fix

* [arellano] use namedtuple

* further_edits

* Merge branch 'use_namedtuple_arellano' of https://github.com/QuantEcon/lecture-jax into use_namedtuple_arellano

* tidyup

* further_tidyup

* edits

* minor_edits

* misc

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Co-authored-by: John Stachurski <john.stachurski@gmail.com>

Author: shlff