Stop using the self global

high priority, frequently broken by changes:

• back up global self into local this for every function that was using it

• replace all self assignments with setself (which currently does the same thing, but is easier to search for and can be changed to do other things, like not compile)

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less urgent, can be done long term post merge:

• replace setself with WITH

• replace SELFPARAM with an actual parameter for functions the engine doesn't need to call