The use of integer types from inttypes.h & stdint.h should help with
portability issues. It will also force the data transmission between
different architectures to work as intended (if we handle endianess
conversions correctly!).
Move code related to sending requests into the new library
libowlps-client. This library will also be used by the listener to send
autocalibration requests.
Currently, it is statically linked because a dynamic linking should be
useless (because client and listener aren't normally on the same
machine).