test(tests/lua): extra tests for Lua hierachical name API

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(kernel/free_vars): make sure has_free_var does not return incorrect result due to arithmetic overflows

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(kernel/instantiate): relax apply_beta pre-condition

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(library/hop_match): bugs in the higher-order matching procedure, add more tests

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>