Fix wrong behaviour of cloning w.r.t. axioms proofs

When using `clone ... proof ...`, more specific proof specifications
have priority over less specific ones.

[fix #17122].
In `rnd E d1 d2 d3 d4`, require the the di's are between 0 && 1.

[#address 17120]
Internals: assertion failure -> typing error

When typing `={...}`, raise a typing exn when the memories &1/&2 do not
exists. [fix #17123]
improve notify (not sure to well understand).
[fix #17089] 
also add small warning to explain why the tactic fail.
Move toolchain to 4.02.1 + opam to 1.2

EasyCrypt OPAM repository now contains only the EC specific packages and
use the main opam repository for other packages.
ec-build-toolchain: parallel jobs + opam init for system installation.
Merge branch '1.0' of git://ci.easycrypt.info/easycrypt into 1.0