use nullptr and float constants

code/AssetLib/glTF/glTFCommon.cpp

@@ -54,7 +54,7 @@ size_t DecodeBase64(const char *in, size_t inLength, uint8_t *&out) {
     }
 
     if (inLength < 4) {
-        out = 0;
+        out = nullptr;
         return 0;
     }
 

code/AssetLib/glTF/glTFCommon.h

@@ -107,7 +107,6 @@ public:
             f(file) {}
     ~IOStream() {
         fclose(f);
-        f = 0;
     }
 
     size_t Read(void *b, size_t sz, size_t n) { return fread(b, sz, n, f); }