16.2.0 release candidate testing

We don't plan to release 16.1.2 anytime soon, but its good to have such page to store notes of things which should be tested.

Notes from testing 16.1.3 are in #307 (closed) .

floating point quirks

• underflow – ieee-floats, mysql-tests libraries have problem with this exception untrapped (src/c/unixint.d:install_fpe_signal_handlers) – we don't trap underflow (same as ccl and sbcl)

• windows doesn't like inexact exception, so we have disabled fpe signal handling and ieee-fp on mingw and msvc. Alternatively we could just turn off trap of sigfpe with ECL_OPT_TRAP_SIGFPE(?)

• format doesn't distinguish between signed zero and normal zero -0.0 v 0.0