Copy over INSTANCE_TT when duping class

Use size_t to calculate bytes needed for array.

Interpret argument in 'f ()' as nil instead of nothing

PR #3293 just checks for NoMethodError.

Safeguard against using MRB_INT64 with MRB_WORD_BOXING in 32-bit mode

Added documentation on function for globals

Fixed NaN boxing when MRB_INT16 is set

Fix incompatibility for Enumerable#first

Fix null pointer dereference in mrb_time_initialize

Fix typo in istruct.h

Reported by https://hackerone.com/raydot