inttypes.h is not necessary, only stdint.h is, so just include that.

This fixes support for some microcontrollers that don't have inttypes.h in their standard library.
Only issue is that Microsoft's Visual Studio/C++ < 2010 don't have stdint.h, but I don't think that's a supported platform at this point.

I purposefully left MAVLink version 0.9 out of this change, because it's deprecated and old and I don't want to break things for old users of the library.