like /tools/mspsim.
This is a very simple modification that affects a very large number of files in Contiki: Cooja,
/platform/cooja, Collect-view, Coffe-manager, and Cooja simulation files (.csc).
I've gone through Contiki to update all references I could find. Nevertheless, this commit will likely
break external dependencies, like saved Cooja simulation files.
declarations of functions for setting and getting a node ID number, a
functionality that exists on many platforms. Since this functionality
was not considered part of the Contiki core, each platform defined its
own node-id.h file. This commit attempts to clean this up by
collecting the node-id.h into a core/sys/node-id.h file that replaces
the old node-id.h files from the platform directories.
