owlps-positioning/Makefile used to use colorgcc as the default compiler,
without testing its existence. This is fixed.
The makefiles for libowlps and infrastructure-centred modules now use
colorgcc when available.
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).