GCC warnings fix

src/coders/png.cpp

@@ -105,7 +105,11 @@ ImageData* _png_load(const char* file){
     if (!(f = fopen(file, "r"))) {
         return nullptr;
     }
-    fread(header, 1, 8, f);
+    if (fread(header, 1, 8, f) < 8) {
+		fclose(f);
+		return nullptr;
+	}
+	
     is_png = !png_sig_cmp(header, 0, 8);
     if (!is_png) {
         fclose(f);

src/files/binary_io.cpp

@@ -60,7 +60,12 @@ void BinaryWriter::putInt64(int64_t val) {
 }
 
 void BinaryWriter::putFloat32(float val) {
-    putInt32(*((uint32_t*)&val));
+    union {
+        int32_t vali32;
+        float valfloat;
+    } value;
+    value.valfloat = val;
+    putInt32(value.vali32);
 }
 
 BinaryReader::BinaryReader(const ubyte* data, size_t size)
@@ -122,8 +127,12 @@ int64_t BinaryReader::getInt64() {
 }
 
 float BinaryReader::getFloat32() {
-    int32_t value = getInt32();
-    return *(float*)(&value);
+    union {
+        int32_t vali32;
+        float valfloat;
+    } value;
+    value.vali32 = getInt32();
+    return value.valfloat;
 }
 
 string BinaryReader::getString() {