Merge branch 'TimePath/global_self' into 'master'

Merge branch 'TimePath/global_self' into 'master'

Stop using the self global

high priority, frequently broken by changes:

- [x] back up global `self` into local `this` for every function that was using it

- [x] 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

See merge request !134