DoGetterProperty and DoSetterProperty

[prepare]

see #40 (comment)

[dpwhittaker]

I believe this is in reference to:

One more issue I've identified. When there are more than 127 property accessors in the sytem, the native side starts looking for negative mIndexes in DoGetterProperty and DoSetterProperty. Turned out this was due to the BinaryStreamReader decoding bytes as chars instead of unsigned chars. I switched all the chars to unsigned chars and the problem went away.

The fix is literally replace the 6 lines in mini_BinaryReaderWriter.cpp that look like:
char byte0 = this->stream[start];
with:
unsigned char byte0 = this->stream[start];