write an interface to world_prop, and make iris_core (assertion logic + world satisfaction) work with it

proofs. One change to axiomatisation was needed.

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On branch coq-ho
Changes not staged for commit:
	modified:   coq-ho/core_lang.v
Untracked files:
	coq-ho/Makefile
no changes added to commit (use "git add" and/or "git commit -a")

more view-shifts), stated lemmas about hoare triples.

definitions pushed through, some lemmas commented out for now.

(open, close, transitive, false), stated some other.