Bugfixes

Fixes for bugs I noticed recently when rebasing my C++ build branch onto master. Some of them I only noticed/fixed by introducing a realloc-wrapping macro (like our calloc and memset() to 0 macros) and the automatic type safety it provides when building as C++ (using the same type for the cast as for the size calculation).

With the exception of the commit that adds that macro, all the rest of these commits fix things that are unambiguously wrong.