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/GltfSerializer.cpp

@@ -23,6 +23,8 @@
 
 #include "../ifcparse/utils.h"
 
+#include <cstdint>
+
 #ifdef WITH_PROJ
 #include <proj.h>
 #endif