Add missing standard library includes for self-sufficient headers

Fixes builds with newer GCC/libstdc++ that no longer provide <cstdint>,
<cstring>, <cfloat>, <memory>, <algorithm> etc. transitively. Also
disambiguates visit<> calls in taxonomy.h with the full namespace and
casts the character value in IfcCharacterDecoder to uint32_t to silence
ambiguous overload warnings.

src/serializers/HdfSerializer.cpp

@@ -34,6 +34,7 @@
 #include <numeric>
 #include <functional>
 #include <cmath>
+#include <cstdint>
 
 #ifdef USE_BINARY
 #define write_shape write_binary