[communication] Modifies the superBus API to separate the really static files from the usage-dependent ones.
* Creates the network_config folder in the repository.
* Moves the networks_cfg.{c,h} files in network_config.
* Splits the former messages.{c,h} files in a static part (messages_header.h in superBus/shared/ ) and in a "usage-dependent" part (messages.{c,h} in network_config/ )
* Introduces a node_cfg.h file for every node.
* Creates the node_cfg.h files for several projects.
* Modifies several source files to match the new files (lib_I2C_arduino.cpp, lib_superBus.c, Xbee4sb.c, Xbee_API.c, ).
* Modifies the README_SUPERBUS.
* Modifies the project properties in balise_mobile and balise_principal.
* creates example config files in superBus/shared/example config files.