Off by one error in resource name check

[antisvin]

Based on forum discussion: https://community.rebeltech.org/t/witch-error-0x60-invalid-save-name-quadsampler/2096

Resource name is QuadSampler.cfg, so 15 bytes + null byte

This can fit into 16 byte Resource::name field, but we demand strictly less than 16 bytes instead of <= 16.

We use strlcpy function to verify that resource name is null terminated, so extra checks due to this change are not necessary