Simplifying the calculus for easier consumption

[ahubers]

Proposal

I propose we simplify the Rome calculus as much as we can, so that:

• we have spend less time (and space) in the text rehashing Rose19 and R-omega23
• the critical reviewer will see the paper less as leaching its merit from previous work
• it is easier to follow Rome solves particular challenges w.r.t. extensible recursion, and is not intended to be a novel calculus

How to simplify

• Remove multi-rows, row theories; work in the minimal row theory + commutativity
• Remove type equivalence
• Stay impredicative & operational
• ...