This command adds a long double to the
specified packet. Typically long doubles are 8 bytes in size and range
from 1.79769e+308 to 2.22507e-308.
The data will be added starting at the cursor position and the cursor will be moved forward by the size of the data added.
long long int Packet: This is the packet that the command should use.
long double: This is the data to be added.
0 if no error occurred.
-1 if an error occurred.
C++