VM: refactored factor_vm::unbox_array_size()
VM: allot_array_1, allot_array_2 are unused and primitive_array should use allot_array
VM: bignum_to_fixnum_strict and an accompanying vm error in case the conversion fails
VM: tests that rely on the integer values of the vm_error_type needs to be updated
VM: better version of bignum_to_fixnum_strict that doesn't allocate
kernel.private: add ERROR-OUT-OF-FIXNUM-RANGE on the Factor side
compiler.cfg.intrinsics.simd: remove a case in sign-bit-mask that is probably unused
compiler.cfg.intrinsics.simd: the ulonglong case is correct, it just shouldn't convert the value to a fixnum
VM: CELL_TO_FOO macro-magic in the same spirit as BIGNUM_TO_FOO

Now also factor_vm::to_cell doesn't piggyback on
factor_vm::to_fixnum's (strict) conversion.
vm: using bignum>fixnum-strict in integer>fixnum-strict.
classes.tuple: fix test-case.
math: remove out-of-fixnum-range error.
kernel: remove ?execute, not used much, and a little bit confusing.