Fixed a few minor issues in 4DGL library Moved pc serial port object used for debug output into 4DGL object itself. Previously it was a global object but its constructor wasn't getting run before the global constructor for the 4DGL object itself which led to an assert in the serial code. I also fixed a few potential buffer overruns that I saw in the code as well.

TFT_4DGL_Graphics.cpp/shortlog@d6e186427f3e: not found in manifest