Now use (int,void*) callbacks instead of (void*,void*) ones.
The implementation was ways too messy to actually work, I guess.
+SMPI:
+ - Change the way SMPI_SAMPLE_* macros work to avoid invalidating cache
+ too often and provide more accurate timings.
+
XBT:
- Drop sg_cmdline. Please use xbt_cmdline instead.
- Drop the C xbt_os_mutex_t; Use the C++11 std::mutex.
