v4.1.0

Caesar 4.1 fixes soundness bugs in @ast, @past, and @omega_invariant that could let invalid proofs pass verification.
It also introduces @uwlp, extends @ast to finite demonic nondeterminism, infers loop terminators, and adds HeyVL reference hovers in Visual Studio Code.

Recheck termination and ω-invariant proofs:

Earlier versions could accept invalid proofs using @ast, @past, or @omega_invariant.
Re-run their verification after upgrading.

In this release:

1. Almost-Sure Termination: @ast
2. Positive Almost-Sure Termination: @past
3. ω-Invariants: @omega_invariant
4. Unbounded Liberal Pre-expectations: @uwlp
5. Simpler Loop Unrolling
6. Visual Studio Code
7. Other Fixes