feat(kernel): add is_bool predicate

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(library/tactic/goal): typo

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(bindings/lua): add proof_state to Lua API

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(bindings/lua): add proof_state to Lua API