first try at killing GRAS -- does not compile yet
Since cmake 2.6, else() and endif() don't need to repeat the condition. And all CMakeLists.txt already require a version of cmake >= 2.6.
Remove usage of environment variable ARGS in tesh files. It is nowadays never used, and such a generic name can be source of problems (it could be defined for other purposes).
Add setenv GRAS_NO_WARN_EXPERIMENTAL=1 for gras tests. The purpose is to deactivate the warning about the experimental status of GRAS, which was making all tests to fail.
Move datadesc and TCP sockets from GRAS to XBT. XBT supports sockets with explicit choice of the transport plugin. XBT provides only one transport plugin: TCP (i.e. real sockets) and allows other layers to write their custom plugins. GRAS implements such custom plugins: simulated sockets and file sockets. TCP sockets only existed in GRAS RL mode. They can now also be used in GRAS SG mode. More pieces of GRAS remain to be moved to XBT before TCP sockets can also be used outside GRAS (e.g. in SIMIX 3, one day, to distribute the simulation).